Aspiration catheter systems and methods of use

ABSTRACT

Described are methods, systems, devices for facilitation of intraluminal medical procedures within the neurovasculature. A catheter advancement device includes a flexible elongate body having a proximal portion coupled to a proximal end region of the flexible elongate body and extending proximally to a proximal-most end of the catheter advancement element. A hardness of the flexible elongate body transitions proximally towards increasingly harder materials up to the proximal portion forming a first plurality of material transitions. At least a portion of the flexible elongate body is formed of a plurality of layers including a reinforcement layer. An outer diameter of the flexible elongate body is sized to be positioned coaxially within a lumen of a catheter such that a distal tip portion of the flexible elongate body extends distally beyond a distal end of the catheter to aid in delivery of the catheter to an intracranial vessel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. application Ser.No. 17/677,548, filed Feb. 22, 2022, which is a continuation ofco-pending U.S. application Ser. No. 17/319,943, filed May 13, 2021,which is a continuation of U.S. application Ser. No. 15/866,012, filedJan. 9, 2018, now U.S. Pat. No. 11,020,133, which claims the benefit ofpriority under 35 U.S.C. § 119(e) to U.S. Provisional Patent ApplicationSer. Nos. 62/444,584, filed Jan. 10, 2017, and 62/607,510, filed Dec.19, 2017. The disclosures are incorporated by reference in theirentireties.

FIELD

The present technology relates generally to medical devices and methods,and more particularly, to aspiration catheter systems and their methodsof use.

BACKGROUND

Acute ischemic stroke (AIS) usually occurs when an artery to the brainis occluded, preventing delivery of fresh oxygenated blood from theheart and lungs to the brain. These occlusions are typically caused by athrombus or an embolus lodging in the artery and blocking the arterythat feeds a territory of brain tissue. If an artery is blocked,ischemia then injury follows, and brain cells may stop working.Furthermore, if the artery remains blocked for more than a few minutes,the brain cells may die, leading to permanent neurological deficit ordeath. Therefore, immediate treatment is critical.

Two principal therapies are employed for treating ischemic stroke:thrombolytic therapy and endovascular treatment. The most commontreatment used to reestablish flow or re-perfuse the stroke territory isthe use of intravenous (IV) thrombolytic therapy. The timeframe to enactthrombolytic therapy is within 3 hours of symptom onset for IV infusion(4.5 hours in selected patients) or within 6 hours for site-directedintra-arterial infusion. Instituting therapy at later times has noproven benefit and may expose the patient to greater risk of bleedingdue to the thrombolytic effect. Endovascular treatment most commonlyuses a set of tools to mechanically remove the embolus, with our withoutthe use of thrombolytic therapy.

The gamut of endovascular treatments include mechanical embolectomy,which utilizes a retrievable structure, e.g., a coil-tipped retrievablestent (also known as a “stent retriever” or a STENTRIEVER), a woven wirestent, or a laser cut stent with struts that can be opened within a clotin the cerebral anatomy to engage the clot with the stent struts, createa channel in the emboli to restore a certain amount of blood flow, andto subsequently retrieve the retrievable structure by pulling it out ofthe anatomy, along with aspiration techniques. Other endovasculartechniques to mechanically remove AIS-associated embolus include ManualAspiration Thrombectomy (MAT) (also known as the “ADAPT” technique).ADAPT/MAT is an endovascular procedure where large bore catheters areinserted through the transfemoral artery and maneuvered through complexanatomy to the level of the embolus, which may be in the extracranialcarotids, vertebral arteries, or intracranial arteries. Aspirationtechniques may be used to remove the embolus through the large borecatheters. Another endovascular procedure is Stentriever-Mediated ManualAspiration Thrombectomy (SMAT) (similar to the Stentriever-assisted“Solumbra” technique). SMAT, like MAT, involves accessing the embolusthrough the transfemoral artery. After access is achieved, however, aretrievable structure is utilized to pull the embolus back into a largebore catheter.

To access the cerebral anatomy, guide catheters or guide sheaths areused to guide interventional devices to the target anatomy from anarterial access site, typically the femoral artery. The length of theguide is determined by the distance between the access site and thedesired location of the guide distal tip. Interventional devices such asguidewires, microcatheters, and intermediate catheters used forsub-selective guides and aspiration, are inserted through the guide andadvanced to the target site. Often, devices are used in a co-axialfashion, namely, a guidewire inside a microcatheter inside anintermediate catheter is advanced as an assembly to the target site in astepwise fashion with the inner, most atraumatic elements, advancingdistally first and providing support for advancement of the outerelements. The length of each element of the coaxial assemblage takesinto account the length of the guide, the length of proximal connectorson the catheters, and the length needed to extend from the distal end.

Typical tri-axial systems such as for aspiration or delivery of stentretrievers and other interventional devices require overlapped series ofcatheters, each with their own rotating hemostatic valves (RHV) on theproximal end. For example, a guidewire can be inserted through aPenumbra Velocity microcatheter having a first proximal RHV, which canbe inserted through a Penumbra ACE68 having a second proximal RHV, whichcan be inserted through a Penumbra NeuronMAX 088 access catheter havinga third proximal RHV positioned in the high carotid via a femoralintroducer. Maintaining the coaxial relationships between thesecatheters can be technically challenging. The three RHVs must beconstantly adjusted with two hands or, more commonly, four hands (i.e.two operators). Further, the working area of typical tri-axial systemsfor aspiration and/or intracranial device delivery can require workingarea of 3-5 feet at the base of the operating table.

The time required to access the site of the occlusion and restore evenpartially flow to the vessel is crucial in determining a successfuloutcome of such procedures. Similarly, the occurrence of distal emboliduring the procedure and the potentially negative neurologic effect andprocedural complications such as perforation and intracerebralhemorrhage are limits to success of the procedure. There is a need for asystem of devices and methods that allow for rapid access, optimizedcatheter aspiration, and treatment to fully restore flow to the blockedcerebral vessel.

SUMMARY

In an aspect, described is an intravascular catheter advancement devicefor facilitation of intraluminal medical procedures within theneurovasculature. The catheter advancement device includes a flexibleelongate body having a proximal end region, an outer diameter, a tapereddistal tip portion, a distal opening, and a single lumen extendinglongitudinally through the flexible elongate body to the distal opening;and a proximal portion coupled to the proximal end region of theflexible elongate body. The proximal portion extends proximally to aproximal-most end of the catheter advancement element. A hardness of theflexible elongate body transitions proximally towards increasinglyharder materials up to the proximal portion forming a first plurality ofmaterial transitions. At least a portion of the flexible elongate bodyis formed of a plurality of layers including a reinforcement layer. Theouter diameter of the flexible elongate body is sized to be positionedcoaxially within a lumen of a catheter such that the distal tip portionof the flexible elongate body extends distally beyond a distal end ofthe catheter to aid in delivery of the catheter to an intracranialvessel.

The reinforcement layer can be a braid. The braid can extend from theproximal end region of the flexible elongate body and terminate at apoint proximal to the distal tip portion. The point can be locatedbetween 4 cm and 15 cm from a distal-most terminus of the flexibleelongate body. The plurality of layers can further include a firstpolymer material layer and a second polymer material layer. The braidcan be positioned between the first and second polymer material layers.The proximal portion can be a hypotube having a distal end coupled tothe flexible elongate body. The braid can be positioned between thefirst and second polymer material layers and positioned over the distalend of the hypotube.

The distal tip portion can include a material having a material hardnessthat is no more than 35 D. The proximal end region of the elongate bodycan include a material having a material hardness that is between 55 Dto 72 D. The elongate body can include a first segment including thedistal tip portion having a hardness of no more than 35 D. The elongatebody can include a second segment located proximal to the first segmenthaving a harness of no more than 55 D. The elongate body can include athird segment located proximal to the second segment having a harness ofno more than 72 D. The proximal portion can couple to the elongate bodywithin the third segment. The first segment can be unreinforced and thethird segment can be reinforced. The second segment can be at leastpartially reinforced. A reinforcement braid can extend through at leastthe third segment. The first, second, and third segments can combine toform an insert length of the elongate body. The first segment can have alength of about 4 cm to about 12.5 cm. The second segment can have alength of about 5 cm to about 8 cm. The third segment can have a lengthof about 25 cm to about 35 cm.

The system can further include the catheter having the lumen and thedistal end. The catheter can include a flexible distal luminal portionhaving a proximal end, a proximal end region, and a proximal opening.The lumen can extend between the proximal end and the distal end. Thecatheter can further include a proximal extension extending proximallyfrom a point of attachment adjacent the proximal opening. The proximalextension can be less flexible than the flexible distal luminal portionand can be configured to control movement of the catheter. The proximalextension can have an outer diameter at the point of attachment that issmaller than an outer diameter of the distal luminal portion at thepoint of attachment. A material hardness of the flexible distal luminalportion can transition proximally towards increasingly harder materialsup to the proximal extension. The flexible distal luminal portion caninclude a second plurality of material transitions. The flexibleelongate body can be coaxially positioned within the lumen of thecatheter such that the distal tip portion of the flexible elongate bodyextends distally beyond the distal end of the catheter such that thefirst plurality of material transitions of the flexible elongate bodyare staggered relative to and do not overlap with the second pluralityof material transitions of the flexible distal luminal portion.

The catheter can be packaged with the device coaxially positioned withinthe lumen of the catheter such that the proximal portion of the flexibleelongate body is locked with the proximal extension of the catheter. Atleast a portion of the proximal extension of the catheter can becolor-coded.

The single lumen of the flexible elongate body can be sized toaccommodate a guidewire. The flexible elongate body can include aproximal opening sized to accommodate the guidewire. The proximalopening can be located within the proximal end region of the flexibleelongate body. The proximal opening can be through a sidewall of theflexible elongate body and located a distance distal to the proximalportion coupled to the proximal end region. The distance can be about 10cm from the distal tip portion up to about 20 cm from the distal tipportion. The proximal portion can have an outer diameter that is smallerthan the outer diameter of the flexible elongate body. The proximalportion can be a hypotube. The device can be configured to be advancedtogether with the catheter after the distal end of the catheter isdistal to the petrous portion of the internal carotid artery.

In an interrelated aspect, disclosed is a method of performing a medicalprocedure in a cerebral vessel of a patient including inserting anassembled coaxial catheter system into a blood vessel of a patient. Theassembled coaxial catheter system includes a catheter and a catheteradvancement element. The catheter includes a flexible distal luminalportion having a proximal end, a proximal end region, a proximalopening, a distal end, and a lumen extending between the proximal endand the distal end; and a proximal extension extending proximally from apoint of attachment adjacent the proximal opening. The proximalextension is less flexible than the flexible distal luminal portion andis configured to control movement of the catheter. The proximalextension has an outer diameter at the point of attachment that issmaller than an outer diameter of the distal luminal portion at thepoint of attachment. The catheter advancement element includes aflexible elongate body having a proximal end region, an outer diameter,a tapered distal tip portion, a distal opening, and a single lumenextending longitudinally through the flexible elongate body to thedistal opening; and a proximal portion extending proximally from theproximal end region to a proximal-most end of the catheter advancementelement. When assembled, the catheter advancement element extendsthrough the catheter lumen and the tapered distal tip portion extendsdistal to the distal end of the distal luminal portion. The methodfurther includes advancing the assembled catheter system until thedistal end of the distal luminal portion reaches a target site withinthe cerebral vessel and the point of attachment between the distalluminal portion and the proximal extension is positioned proximal to thebrachiocephalic take-off in the aortic arch. The method further includesremoving the catheter advancement element from the lumen of thecatheter; and removing occlusive material while applying a negativepressure to the lumen of the catheter.

The distal end of the distal luminal portion can be positioned distal tothe carotid siphon when the point of attachment is positioned proximalto the brachiocephalic take-off within the aortic arch. The distalluminal portion can have a length between 35 cm and 60 cm. The proximalportion of the catheter advancement element can be coupled to theproximal end region of the flexible elongate body at a point ofattachment, the proximal portion extending proximally from the point ofattachment to the proximal-most end of the catheter advancement element.The proximal portion can have a single lumen extending through an entirelength of the proximal portion that communicates with the single lumenof the elongate body. The elongate body can have a length sufficient toallow the point of attachment between the elongate body and the proximalportion to remain within or proximal to the aortic arch when assembledwith the catheter. The distal end of the catheter can be positioned nearthe target site within the cerebral vessel.

The assembled catheter system can be pre-packaged with the catheteradvancement element coaxially positioned within the lumen of the distalluminal portion such that the proximal portion of the flexible elongatebody is locked with the proximal extension of the catheter. At least aportion of the proximal extension of the catheter can be color-coded.The single lumen of the flexible elongate body can be sized toaccommodate a guidewire. The flexible elongate body can include aproximal opening sized to accommodate the guidewire. The proximalopening can be located within the proximal end region of the flexibleelongate body. The proximal opening can be through a sidewall of theflexible elongate body and can be located a distance distal to theproximal portion coupled to the proximal end region. The distance can beabout 10 cm from the distal tip portion up to about 20 cm from thedistal tip portion. A hardness of the flexible elongate body cantransition proximally towards increasingly harder materials up to theproximal portion forming a first plurality of material transitions. Atleast a portion of the flexible elongate body can be formed of aplurality of layers including a reinforcement layer. The reinforcementlayer can be a braid. The braid can extend from the proximal end regionof the flexible elongate body and terminate at a point proximal to thedistal tip portion. The point can be located between 4 cm and 15 cm froma distal-most terminus of the flexible elongate body. The plurality oflayers can further include a first polymer material layer and a secondpolymer material layer. The braid can be positioned between the firstand second polymer material layers. The proximal portion can be ahypotube having a distal end coupled to the flexible elongate body. Thebraid positioned between the first and second polymer material layers ispositioned over the distal end of the hypotube.

The distal tip portion can include a material having a material hardnessthat is no more than 35 D. The proximal end region of the elongate bodycan include a material having a material hardness that is between 55 Dto 72 D. The elongate body can include a first segment including thedistal tip portion having a hardness of no more than 35 D. The elongatebody can include a second segment located proximal to the first segmenthaving a harness of no more than 55 D. The elongate body can include athird segment located proximal to the second segment having a harness ofno more than 72 D. The proximal portion can couple to the elongate bodywithin the third segment. The first segment can be unreinforced and thethird segment can be reinforced. The second segment can be at leastpartially reinforced. A reinforcement braid can extend through at leastthe third segment. The first, second, and third segments can combine toform an insert length of the elongate body. The first segment can have alength of about 4 cm to about 12.5 cm. The second segment can have alength of about 5 cm to about 8 cm. The third segment can have a lengthof about 25 cm to about 35 cm. A material hardness of the flexibledistal luminal portion can transition proximally towards increasinglyharder materials up to the proximal extension. The flexible distalluminal portion can include a second plurality of material transitions.The flexible elongate body can be coaxially positioned within the lumenof the catheter such that the distal tip portion of the flexibleelongate body extends distally beyond the distal end of the cathetersuch that the first plurality of material transitions of the flexibleelongate body are staggered relative to and do not overlap with thesecond plurality of material transitions of the flexible distal luminalportion.

In an interrelated aspect, described is a method of performing a medicalprocedure in a cerebral vessel of a patient including inserting a guidesheath into a blood vessel. The guide sheath include a lumen extendingbetween a proximal end region and a distal end region of the guidesheath, the distal end region of the guide sheath having an opening incommunication with the lumen of the guide sheath. The method includespositioning the guide sheath such that the distal end region of theguide sheath is positioned within at least to a level of the commoncarotid artery. The method includes inserting an intermediate catheterthrough the lumen of the guide sheath. The intermediate catheterincludes a lumen and a distal opening at a distal end of theintermediate catheter. The method includes advancing the intermediatecatheter such that the distal end of the intermediate catheter isadvanced through the opening of the guide sheath and beyond the distalend region of the guide sheath. The method includes inserting a distalaccess catheter through the lumen of the intermediate catheter. Thedistal access catheter includes a flexible distal luminal portion havinga proximal end, a proximal end region, a proximal opening, a distal end,and a lumen extending between the proximal end and the distal end; and aproximal extension extending proximally from a point of attachmentadjacent the proximal opening. The proximal extension is less flexiblethan the flexible distal luminal portion and is configured to controlmovement of the catheter. The proximal extension has an outer diameterat the point of attachment that is smaller than an outer diameter of theflexible distal luminal portion at the point of attachment. The methodfurther includes advancing the distal access catheter such that thedistal end of the flexible distal luminal portion is advanced throughthe distal opening of the intermediate catheter and beyond the distalend of the intermediate catheter.

The distal end region of the guide sheath can include an inflatableocclusion balloon. The method can further include inflating theocclusion balloon to occlude antegrade flow through the common carotidartery. The distal end region of the guide sheath can have an unlined,unreinforced region configured to seal onto an outer surface of theintermediate catheter. The distal access catheter can be assembled witha catheter advancement element forming an assembled coaxial cathetersystem prior to the advancing step. The catheter advancement elementincludes a flexible elongate body having a proximal end region, an outerdiameter, a tapered distal tip portion, a distal opening, and a singlelumen extending longitudinally through the flexible elongate body to thedistal opening; and a proximal portion extending proximally from theproximal end region to a proximal-most end of the catheter advancementelement.

When assembled, the catheter advancement element can extend through thelumen of the distal luminal portion and the tapered distal tip portioncan extend distal to the distal end of the distal luminal portion. Themethod can further include advancing the assembled coaxial cathetersystem until the distal end of the distal luminal portion reaches atarget site within the cerebral vessel and the point of attachmentbetween the distal luminal portion and the proximal extension ispositioned proximal to the brachiocephalic take-off in the aortic arch.The method can further include removing the catheter advancement elementfrom the lumen of the catheter; and removing occlusive material whileapplying a negative pressure to the lumen of the catheter.

The assembled catheter system can be pre-packaged with the catheteradvancement element coaxially positioned within the lumen of the distalluminal portion such that the proximal portion of the flexible elongatebody is locked with the proximal extension of the catheter. At least oneof the intermediate catheter and the distal access catheter can furtherinclude a tab to prevent over-insertion of the catheter relative to thelumen through which it extends. At least one of the intermediatecatheter and the distal access catheter can further include adistinguishable color-coded element. The single lumen of the flexibleelongate body can be sized to accommodate a guidewire. The flexibleelongate body can include a proximal opening sized to accommodate theguidewire. The proximal opening can be located within the proximal endregion of the flexible elongate body. The proximal opening can bethrough a sidewall of the flexible elongate body and can be located adistance distal to the proximal portion coupled to the proximal endregion. The distance can be about 10 cm from the distal tip portion upto about 20 cm from the distal tip portion.

The intermediate catheter can be assembled with a catheter advancementelement forming an assembled coaxial catheter system prior to theadvancing step. The catheter advancement element can include a flexibleelongate body having a proximal end region, an outer diameter, a tapereddistal tip portion, a distal opening, and a single lumen extendinglongitudinally through the flexible elongate body to the distal opening;and a proximal portion extending proximally from the proximal end regionto a proximal-most end of the catheter advancement element. Whenassembled, the catheter advancement element can extend through the lumenof the intermediate catheter and the tapered distal tip portion canextend distal to the distal end of the intermediate catheter. Theintermediate catheter can include a flexible distal luminal portion anda proximal extension extending proximally from a point of attachmentadjacent a proximal opening in the flexible distal luminal portion. Theproximal extension can be less flexible than the flexible distal luminalportion of the intermediate catheter and have an outer diameter that issmaller than an outer diameter of the proximal elongate body.

In some variations, one or more of the following can optionally beincluded in any feasible combination in the above methods, apparatus,devices, and systems. More details of the devices, systems, and methodsare set forth in the accompanying drawings and the description below.Other features and advantages will be apparent from the description anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects will now be described in detail with referenceto the following drawings. Generally speaking the figures are not toscale in absolute terms or comparatively, but are intended to beillustrative. Also, relative placement of features and elements may bemodified for the purpose of illustrative clarity.

FIGS. 1A-1B illustrate the course of the terminal internal carotidartery through to the cerebral vasculature;

FIG. 1C illustrates the location of the brachiocephalic take-off fromthe aortic arch;

FIG. 2A is an exploded view of an implementation of an aspirationcatheter system;

FIG. 2B is an assembled view of the system of FIG. 2A;

FIG. 2C is a detail view of FIG. 2A taken at circle C-C;

FIG. 2D illustrates an implementation of an arterial access devicehaving a distal occlusion balloon;

FIG. 3 is a side view of an implementation of a catheter;

FIG. 4A is a cross-sectional view of first implementation of a proximalextension of a catheter;

FIG. 4B is a cross-sectional view of another implementation of aproximal extension of a catheter;

FIG. 4C is a cross-sectional view of the proximal extension of FIG. 4Awithin a working lumen of an access sheath;

FIG. 4D is a cross-sectional view of the proximal extension of FIG. 4Bwithin a working lumen of an access sheath having a catheter advancementelement extending therethrough;

FIG. 4E is a cross-sectional, schematic view comparing the surface areaof the proximal extension of FIG. 4A and the proximal extension of FIG.4B within the working lumen of an access sheath of FIG. 4D;

FIGS. 4F-4G are cross-sectional, schematic views comparing trapezoid-and D-shaped proximal extensions, respectively, relative to a workinglumen of an access sheath;

FIG. 5A is a side elevational view of an implementation of a catheter;

FIG. 5B is a top plan view of the catheter of FIG. 5A;

FIG. 5C is a cross-sectional view of the catheter taken along line C-Cof FIG. 5B;

FIG. 5D is a cross-sectional view of the catheter taken along line D-Dof FIG. 5B;

FIGS. 5E-5F are partial perspective views of the catheter of FIG. 5A;

FIG. 6A is a side elevational view of an implementation of a catheter;

FIG. 6B is a top plan view of the catheter of FIG. 6A;

FIG. 6C is a cross-sectional view of the catheter taken along line C-Cof FIG. 6B;

FIG. 6D is a cross-sectional view of the catheter taken along line D-Dof FIG. 6B;

FIGS. 6E-6F are partial perspective views of the catheter of FIG. 6A;

FIG. 7A is a side view of an implementation of a catheter advancementelement;

FIG. 7B is a cross-sectional view of the catheter advancement element ofFIG. 7A;

FIG. 7C is a detail view of FIG. 7B taken along circle C-C;

FIG. 7D is a side view of another implementation of a catheteradvancement element;

FIG. 7E is cross-sectional view of an implementation of a proximalportion the catheter advancement element of FIG. 7D;

FIGS. 7F-7J are various views of an implementation of a proximal hub forcoupling to the proximal portion shown in FIG. 7E;

FIG. 8A is a side view of an implementation of a catheter;

FIG. 8B is a schematic cut-away view of the distal end region of thecatheter of FIG. 8A;

FIG. 8C is a schematic cross-sectional view of the distal end region ofthe catheter of FIG. 8A;

FIG. 9A-9C are various views of a proximal extension connector;

FIG. 10A is a schematic cross-sectional view of an implementation of acatheter advancement element;

FIG. 10B is a schematic cross-sectional view of a distal end region ofthe catheter advancement element of FIG. 10A;

FIG. 10C is a schematic cross-sectional view of a middle region of thecatheter advancement element of FIG. 10A;

FIG. 11 is a schematic of an implementation of a catheter aligned withan implementation of a catheter advancement element illustratingstaggered material transitions;

FIG. 12 is a tear-away disc coupler.

It should be appreciated that the drawings are for example only and arenot meant to be to scale. It is to be understood that devices describedherein may include features not necessarily depicted in each figure.

DETAILED DESCRIPTION

Navigating the carotid anatomy in order to treat various neurovascularpathologies at the level of the cerebral arteries, such as acuteischemic stroke (AIS), requires catheter systems having superiorflexibility and deliverability. The internal carotid artery (ICA) arisesfrom the bifurcation of the common carotid artery (CCA) at the level ofthe intervertebral disc between C3 and C4 vertebrae. As shown in FIG.1A, the course of the ICA is divided into four parts—cervical Cr,petrous Pt, cavernous Cv and cerebral Cb parts. In the anteriorcirculation, the consistent tortuous terminal carotid is locked into itsposition by bony elements. The cervical carotid Cr enters the petrousbone and is locked into a set of turns encased in bone. The cavernouscarotid is an artery that passes through a venous bed, the cavernoussinus, and while flexible, is locked as it exits the cavernous sinus byanother bony element, which surrounds and fixes the entry into thecranial cavity. Because of these bony points of fixation, the petrousand cavernous carotid (Pt and Cv) and above are relatively consistent intheir tortuosity. The carotid siphon CS is an S-shaped part of theterminal ICA. The carotid siphon CS begins at the posterior bend of thecavernous ICA and ends at the ICA bifurcation into the anterior cerebralartery ACA and middle cerebral artery MCA. The ophthalmic artery arisesfrom the cerebral ICA, which represents a common point of catheter hangup in accessing the anterior circulation. These points of catheter hangup can significantly increase the amount of time needed to restore bloodperfusion to the brain, which in the treatment of AIS is a disadvantagewith severe consequences.

With advancing age, the large vessels often enlarge and lengthen. Fixedproximally and distally, the cervical internal carotid often becomestortuous with age. The common carotid artery CCA is relatively fixed inthe thoracic cavity as it exits into the cervical area by the clavicle.The external and internal carotid arteries ECA, ICA are not fixedrelative to the common carotid artery CCA, and thus they developtortuosity with advancing age with lengthening of the entire carotidsystem. This can cause them to elongate and develop kinks and tortuosityor, in worst case, a complete loop or so-called “cervical loop”. Ifcatheters used to cross these kinked or curved areas are too stiff orinflexible, these areas can undergo a straightening that can cause thevessel to wrap around or “barbershop pole” causing focused kinking andfolding of the vessel. These sorts of extreme tortuosity also cansignificantly increase the amount of time needed to restore bloodperfusion to the brain, particularly in the aging population. In certaincircumstances, the twisting of vessels upon themselves or if theuntwisted artery is kinked, normal antegrade flow may be reduced to astandstill creating ischemia. Managing the unkinking or unlooping thevessels such as the cervical ICA can also increase the time it takes toperform a procedure.

A major drawback of current catheter systems for stroke interventionprocedures is the amount of time required to restore blood perfusion tothe brain, including the time it takes to access the occlusive site orsites in the cerebral artery and the time it takes to completely removethe occlusion in the artery. Because it is often the case that more thanone attempt must be made to completely remove the occlusion, reducingthe number of attempts as well as reducing the time required to exchangedevices for additional attempts is an important factor in minimizing theoverall time. Additionally, each attempt is associated with potentialprocedural risk due to device advancement in the delicate cerebralvasculature. Another limitation is the need for multiple operators todeliver and effectively manipulate long tri-axial systems with multipleRHVs typically used with conventional guide and distal access catheters.

Described herein are catheter systems for treating various neurovascularpathologies, such as acute ischemic stroke (AIS). The systems describedherein provide quick and simple single-operator access to distal targetanatomy, in particular tortuous anatomy of the cerebral vasculature at asingle point of manipulation. The medical methods, devices and systemsdescribed herein allow for navigating complex, tortuous anatomy toperform rapid and safe aspiration and removal of cerebral occlusions forthe treatment of acute ischemic stroke. The medical methods, devices andsystems described herein can also be used to deliver intracranialmedical devices, with or without aspiration for the removal of cerebralocclusions in the treatment of acute ischemic stroke. The systemsdescribed herein can be particularly useful for the treatment of AISwhether a user intends to perform stent retriever delivery alone,aspiration alone, or a combination of aspiration and stent retrieverdelivery as a frontline treatment for AIS. Further, the extremeflexibility and deliverability of the distal access catheter systemsdescribed herein allow the catheters to take the shape of the tortuousanatomy rather than exert straightening forces creating new anatomy. Thedistal access catheter systems described herein can pass throughtortuous loops while maintaining the natural curves of the anatomytherein decreasing the risk of vessel straightening. The distal accesscatheter systems described herein can thereby create a safe conduitthrough the neurovasculature maintaining the natural tortuosity of theanatomy for other catheters to traverse (e.g. interventional devicedelivery catheters). The catheters traversing the conduit need not havethe same degree of flexibility and deliverability such that if they weredelivered directly to the same anatomy rather than through the conduit,would lead to straightening, kinking, or folding of the anteriorcirculation.

It should be appreciated that while some implementations are describedherein with specific regard to accessing a neurovascular anatomy ordelivery of treatment devices, the systems and methods described hereinshould not be limited to this and may also be applicable to other uses.For example, the catheter systems described herein may be used todeliver working devices to a target vessel of a coronary anatomy orother vasculature anatomy. It should also be appreciated that where thephrase “aspiration catheter” is used herein that such a catheter may beused for other purposes besides or in addition to aspiration, such asthe delivery of fluids to a treatment site or as a support catheter ordistal access catheter providing a conduit that facilitates and guidesthe delivery or exchange of other devices such as a guidewire orinterventional devices, such as stent retrievers. Alternatively, theaccess systems described herein may also be useful for access to otherparts of the body outside the vasculature. Similarly, where the workingdevice is described as being an expandable cerebral treatment device,stent retriever or self-expanding stent other interventional devices canbe delivered using the delivery systems described herein.

Referring now to the drawings, FIGS. 2A-2B illustrate a system 100including devices for accessing and removing a cerebral occlusion totreat acute ischemic stroke from an access site. The system 100 can be asingle operator system such that each of the components and systems canbe delivered and used together by one operator using minimal handmovements. As will be described in more detail below, all wire andcatheter manipulations can occur at or in close proximity to a singlerotating hemostatic valve (RHV) 434 or more than a single RHV co-locatedin the same device. The system 100 can include one or more of a catheter200, a catheter advancement element 300, and an access guide sheath 400,each of which will be described in more detail below. The catheter 200is configured to be received through the guide sheath 400 and isdesigned to have exceptional deliverability. The catheter 200 can be aspined, distal access catheter co-axial with a lumen of the guide sheath400 thereby providing a step-up in inner diameter within the conduit.The catheter 200 can be delivered using a catheter advancement element300 inserted through a lumen 223 of the catheter 200 forming a catheterdelivery system 150. The system 100 can be a distal access system thatcan create a variable length from point of entry at the percutaneousarteriotomy (e.g. the femoral artery) to the target control point of thedistal catheter. Conventional distal access systems for strokeintervention typically include a long guide sheath or guide catheterplaced through a shorter “introducer” sheath (e.g. 11-30 cm in length)at the groin. The long guide sheath is typically positioned in the ICAto support neurovascular interventions including stroke thrombectomy.For added support, these can be advanced up to the bony terminal petrousand rarely into the cavernous or clinoid or supraclinoid terminal ICAwhen possible. To reach targets in the M1 or M2 distribution forADAPT/MAT or Solumbra/SMAT approaches, an additional catheter isinserted through the long guide catheter. These catheters are typicallylarge-bore aspiration catheters that can be 130 cm in length or longer.As will be described in more detail below, the distal access systems 100described herein can be shorter, for example, only 115 cm in length.Additionally, the single operator can use the systems described hereinby inserting them through a single rotating hemostatic valve (RHV) 434on the guide sheath 400 or more than one RHV co-located in the samedevice such as a dual-headed RHV. Thus, what was once a two-personprocedure can be a one-person procedure.

Each of the various components of the various systems will now bedescribed in more detail.

Access Guide Sheath

Again with respect to FIGS. 2A-2D, the distal access system 100 caninclude an access guide sheath 400 having a body 402 through which aworking lumen extends from a proximal hemostasis valve 434 coupled to aproximal end region 403 of the body 402 to a distal opening 408 of adistal end region. The working lumen is configured to receive thecatheter 200 therethrough such that a distal end of the catheter 200 canextend beyond a distal end of the sheath 400 through the distal opening408. The guide sheath 400 can be used to deliver the catheters describedherein as well as any of a variety of working devices known in the art.For example, the working devices can be configured to provide thrombotictreatments and can include large-bore catheters, aspirationthrombectomy, advanced catheters, wires, balloons, retrievablestructures such as coil-tipped retrievable stents “Stentriever”. Theguide sheath 400 in combination with the catheter 200 can be used toapply distal aspiration as will be described in more detail below.

The guide sheath 400 can be any of a variety of commercially availableguide sheaths. For example, the guide sheath 400 can have an ID between0.087″-0.089″ such as the Cook SHUTTLE 6F (Cook Medical, Inc.,Bloomington, Ind.), Terumo DESTINATION 6F (Terumo Europe NV), CordisVISTA BRITE TIP (Cordis Corp., Hialeah, Fla.), and Penumbra NEURON MAX088 (Penumbra, Inc., Alameda, Calif.), or comparable commerciallyavailable guiding sheath. Generally, sheath sizes are described hereinusing the French (F) scale. For example, where a sheath is described asbeing 6 French, it should be appreciated that the inner diameter of thatsheath is able to receive a catheter having a 6F outer diameter, whichis about 1.98 mm or 0.078″. It should be appreciated, therefore, that acatheter may be described herein as having a particular size in Frenchto refer to the compatibility of its inner diameter to receive an outerdiameter of another catheter. A catheter may also be described herein ashaving a particular size in French to refer to its outer diameter beingcompatible with another catheter having a particular inner diameter.

Again with respect to FIGS. 2A-2D, the catheter body 402 can extend froma proximal furcation or rotating hemostatic valve (RHV) 434 at aproximal end region 403 to a tip 406 at a distal end of the body 402.The proximal RHV 434 may include one or more lumens molded into aconnector body to connect to the working lumen of the body 402 of theguide sheath 400. As described above, the working lumen can receive thecatheter 200 and/or any of a variety of working devices for delivery toa target anatomy. The RHV 434 can be constructed of thick-walled polymertubing or reinforced polymer tubing. The RHV 434 allows for theintroduction of devices through the guide sheath 400 into thevasculature, while preventing or minimizing blood loss and preventingair introduction into the guide sheath 400. The RHV 434 can be integralto the guide sheath 400 or the guide sheath 400 can terminate on aproximal end in a female Luer adaptor to which a separate hemostasisvalve component, such as a passive seal valve, a Tuohy-Borst valve orrotating hemostasis valve may be attached. The RHV 434 can have anadjustable opening that is open large enough to allow removal of devicesthat have adherent clot on the tip without causing the clot to dislodgeat the RHV 434 during removal. Alternately, the RHV 434 can be removablesuch as when a device is being removed from the sheath 400 to preventclot dislodgement at the RHV 434. The RHV 434 can be a dual RHV.

The RHV 434 can form a Y-connector on the proximal end 403 of the sheath400 such that the first port of the RHV 434 can be used for insertion ofa working catheter into the working lumen of the sheath 400 and a secondport into arm 412 can be used for another purpose. For example, asyringe or other device can be connected at arm 412 via a connector 432to deliver a forward drip, a flush line for contrast or salineinjections through the body 402 toward the tip 406 and into the targetanatomy. Arm 412 can also connect to a large-bore aspiration line and anaspiration source (not shown) such as a syringe or pump to draw suctionthrough the working lumen. The arm 412 can also allow the guide sheath400 to be flushed with saline or radiopaque contrast during a procedure.The working lumen can extend from a distal end to a working proximalport of the proximal end region 403 of the catheter body 402.

The length of the catheter body 402 is configured to allow the distaltip 406 of the body 402 to be positioned as far distal in the internalcarotid artery (ICA), for example, from a transfemoral approach withadditional length providing for adjustments if needed. In someimplementations (e.g. femoral or radial percutaneous access), the lengthof the body 402 can be in the range of 80 to 90 cm although it should beappreciated that the of the body 402 can be longer, for example, up toabout 100 cm or up to about 105 cm or up to about 117 cm total. Inimplementations, the body 402 length is suitable for a transcarotidapproach to the bifurcation of the carotid artery, in the range of 20-25cm. In further implementations, the body 402 length is suitable for apercutaneous transcarotid approach to the CCA or proximal ICA, and is inthe range of 10-15 cm. The body 402 is configured to assume and navigatethe bends of the vasculature without kinking, collapsing, or causingvascular trauma, even, for example, when subjected to high aspirationforces.

The tip 406 of the guide sheath 400 can have a same or similar outerdiameter as a section of the body 402 leading up to the distal end.Accordingly, the tip 406 may have a distal face orthogonal to alongitudinal axis passing through the body 402 and the distal face mayhave an outer diameter substantially equal to a cross-sectional outerdimension of the body 402. In an implementation, the tip 406 includes achamfer, fillet, or taper, making the distal face diameter slightly lessthan the cross-sectional dimension of the body 402. In a furtherimplementation, the tip 406 may be an elongated tubular portionextending distal to a region of the body 402 having a uniform outerdiameter such that the elongated tubular portion has a reduced diametercompared to the uniform outer diameter of the body 402. Thus, the tip406 can be elongated or can be more bluntly shaped. Accordingly, the tip406 may be configured to smoothly track through a vasculature and/or todilate vascular restrictions as it tracks through the vasculature. Theworking lumen may have a distal end forming a distal opening 408.

The guide sheath 400 may include a tip 406 that tapers from a section ofthe body 402 leading up to the distal end. That is, an outer surface ofthe body 402 may have a diameter that reduces from a larger dimension toa smaller dimension at a distal end. For example, the tip 406 can taperfrom an outer diameter of approximately 0.114″ to about 0.035″ or fromabout 0.110″ to about 0.035″ or from about 0.106″ to about 0.035″. Theangle of the taper of the tip 406 can vary depending on the length ofthe tapered tip 406. For example, in some implementations, the tip 406tapers from 0.110″ to 0.035″ over a length of approximately 50 mm.

In an implementation, the guide sheath 400 includes one or moreradiopaque markers 411. The radiopaque markers 411 can be disposed nearthe distal tip 406. For example, a pair of radiopaque bands may beswaged, painted, embedded, or otherwise disposed in or on the body 402.In some implementations, the radiopaque markers 411 include a bariumpolymer, tungsten polymer blend, tungsten-filled or platinum-filledmarker that maintains flexibility of the distal end of the device andimproves transition along the length of the guide sheath 400 and itsresistance to kinking. In some implementations, the radiopaque marker411 is a tungsten-loaded PEBAX or polyurethane that is heat welded tothe body 402. The markers 411 are shown in the figures as rings around acircumference of one or more regions of the body 402. However, themarkers 411 need not be rings and can have other shapes or create avariety of patterns that provide orientation to an operator regardingthe position of the distal opening 408 within the vessel. Accordingly,an operator may visualize a location of the distal opening 408 underfluoroscopy to confirm that the distal opening 408 is directed toward atarget anatomy where a catheter 200 is to be delivered. For example,radiopaque marker(s) 411 allow an operator to rotate the body 402 of theguide sheath 400 at an anatomical access point, e.g., a groin of apatient, such that the distal opening provides access to an ICA bysubsequent working device(s), e.g., catheters and wires advanced to theICA. In some implementations, the radiopaque marker(s) 411 includeplatinum, gold, tantalum, tungsten or any other substance visible underan x-ray fluoroscope. It should be appreciated that any of the variouscomponents of the systems described herein can incorporate radiopaquemarkers as described above.

In some implementations, the guide sheath 400 can have performancecharacteristics similar to other sheaths used in carotid access and AISprocedures in terms of kinkability, radiopacity, column strength, andflexibility. The inner liners can be constructed from a low frictionpolymer such as PTFE (polytetrafluoroethylene) or FEP (fluorinatedethylene propylene) to provide a smooth surface for the advancement ofdevices through the inner lumen. An outer jacket material can providemechanical integrity to the inner liners and can be constructed frommaterials such as PEBAX, thermoplastic polyurethane, polyethylene,nylon, or the like. A third layer can be incorporated that can providereinforcement between the inner liner and the outer jacket. Thereinforcement layer can prevent flattening or kinking of the inner lumenof the body 402 to allow unimpeded device navigation through bends inthe vasculature as well as aspiration or reverse flow. The body 402 canbe circumferentially reinforced. The reinforcement layer can be madefrom metal such as stainless steel, Nitinol, Nitinol braid, helicalribbon, helical wire, cut stainless steel, or the like, or stiff polymersuch as PEEK. The reinforcement layer can be a structure such as a coilor braid, or tubing that has been laser-cut or machine-cut so as to beflexible. In another implementation, the reinforcement layer can be acut hypotube such as a Nitinol hypotube or cut rigid polymer, or thelike. The outer jacket of the body 402 can be formed of increasinglysofter materials towards the distal end. For example, proximal region ofthe body 402 can be formed of a material such as Nylon, a region of thebody 402 distal to the proximal region of the body 402 can have ahardness of 72 D whereas areas more distal can be increasingly moreflexible and formed of materials having a hardness of 55 D, 45 D, 35 Dextending towards the distal tip 406, which can be formed of a materialhaving a hardness of no more than 35 D and in some implementationssofter than 35 D. The body 402 can include a hydrophilic coating.

The flexibility of the body 402 can vary over its length, withincreasing flexibility towards the distal portion of the body 402. Thevariability in flexibility may be achieved in various ways. For example,the outer jacket may change in durometer and/or material at varioussections. A lower durometer outer jacket material can be used in adistal section of the guide sheath compared to other sections of theguide sheath. Alternately, the wall thickness of the jacket material maybe reduced, and/or the density of the reinforcement layer may be variedto increase the flexibility. For example, the pitch of the coil or braidmay be stretched out, or the cut pattern in the tubing may be varied tobe more flexible. Alternately, the reinforcement structure or thematerials may change over the length of the elongate body 402. Inanother implementation, there is a transition section between thedistal-most flexible section and the proximal section, with one or moresections of varying flexibilities between the distal-most section andthe remainder of the elongate body 402. In this implementation, thedistal-most section is about 2 cm to about 5 cm, the transition sectionis about 2 cm to about 10 cm and the proximal section takes up theremainder of the sheath length.

The different inner diameters of the guide sheaths 400 can be used toreceive different outer diameter catheters 200. In some implementations,the working lumen of a first guide sheath 400 can have an inner diametersized to receive a 6F catheter and the working lumen of a second guidesheath 400 can have an inner diameter sized to receive an 8F catheter.In some implementations, the distal region of the guide sheath 400 canhave an inner diameter of about 0.087″ to 0.088″. The guide sheaths 400can receive catheters having an outer diameter that is snug to theseinner diameter dimensions. It should be appreciated that the guidesheath 400 (as well as any of the variety of components used incombination with the sheath 400) can be an over-the-wire (OTW) or rapidexchange type device, which will be described in more detail below.

As described above, the sheath 400 can include a body 402 formed ofgenerally three layers, including a lubricious inner liner, areinforcement layer, and an outer jacket layer. The reinforcement layercan include a braid to provide good torqueability optionally overlaid bya coil to provide good kink resistance. In sheaths where thereinforcement layer is a braid alone, the polymers of the outer jacketlayer can be generally higher durometer and thicker to avoid issues withkinking. The wall thickness of such sheaths that are braid alone withthicker polymer can be about 0.011″. The wall thickness of the sheaths400 described herein having a braid with a coil overlay provide bothtorqueability and kink resistance and can have a generally thinner wall,for example, a wall thickness of about 0.0085″. The proximal end outerdiameter can thereby be reduced to about 0.107″ outer diameter. Thus,the sheath 400 is a high performance sheath 400 that has good torque andkink resistance with a thinner wall providing an overall lower profileto the system. The thinner wall and lower profile allows for a smallerinsertion hole through the vessel without impacting overall lumen size.In some implementations, the wall thickness of the guide sheath 400 canslowly step down to be thinner towards a distal end of the sheathcompared to a proximal end.

The guide sheath 400 may include a distal tip 406 that is designed toseal well with an outer diameter of a catheter extending through itsworking lumen. The distal tip 406 can be formed of soft material that isdevoid of both liner and reinforcement layers. The lubricious linerlayer and also the reinforcement layer can extend through a majority ofthe body 402 except for a length of the distal tip 406 (see FIG. 2C).The length of this unlined, unreinforced portion of the distal tip 406of the sheath 400 can vary. In some implementations, the length isbetween about 3 mm to about 6 mm of the distal end region of the sheath400. Thus, the liner 409 of the sheath 400 can terminate at least about3 mm away from the distal-most terminus of the sheath 400 leaving thelast 3 mm unlined soft material forming the distal tip 406. In someimplementations, the coil and braid of the reinforcement layer can havetheir ends held in place by a radiopaque markers 411, such as a markerband positioned near a distal-most terminus of the sheath 400. The linerlayer 409 can extend at least a length distal to the marker band 411before terminating, for example, a length of about 1 mm. The staggeredtermination of the wall layers can aid in the transition from the markerband 411 to the soft polymer material 407 of the distal tip 406. Thesoft polymer material 407 can extend a length beyond the liner layer409. The unlined, soft material 407 forming the distal tip 406 can be aPEBAX material having a durometer of no more than about 40 D, no morethan about 35 D, no more than about 62 A, or no more than about 25 D.The softness of the material and the length of this unlined distal tip406 of the sheath 400 can vary. Generally, the material is soft enoughto be compressed down onto the outer diameter of the catheter 200extending through the lumen of the sheath 400, such as upon applicationof a negative pressure through the lumen. The length of this unlined,unreinforced region 407 of the distal tip 406 is long enough to providea good seal, but not so long as to cause problems with according orfolding over during relative sliding between the sheath 400 and thecatheter 200 that might blocking the sheath lumen or negativelyimpacting slidability of the catheter 200 within the sheath lumen.

The distal tip 406 can have an inner diameter that approaches the outerdiameter of the catheter 200 that extends through the sheath 400. Insome implementations, the inner diameter of the distal tip 406 can varydepending on what size catheter is to be used. For example, the innerdiameter of the sheath at the distal tip 406 can be about 0.106″ whenthe outer diameter of the catheter near the proximal end is about 0.101″such that the difference in diameters is about 0.005″. Upon applicationof a vacuum, the soft unlined and unreinforced distal tip 406 can moveto eliminate this 0.005″ gap and compress down onto the outer diameterof the catheter 200 near its proximal end region upon extension of thecatheter 200 out its distal opening 408. The difference between theinner diameter of the distal tip 406 and the outer diameter of thecatheter can be between about 0.002″-0.006″. The inner diameter of thedistal tip 406 can also be tapered such the inner diameter at thedistal-most terminus of the opening 408 is only 0.001″ to 0.002″ largerthan the outer diameter of the proximal end of the catheter 200extending through the working lumen. In some implementations, the distaltip 406 is shaped such that the walls are beveled at an angle relativeto a central axis of the sheath 400, such as about 60 degrees.

In some instances it is desirable for the sheath body 402 to also beable to occlude the artery in which it is positioned, for example,during procedures that may create distal emboli. Occluding the arterystops antegrade blood flow and thereby reduces the risk of distal embolithat may lead to neurologic symptoms such as TIA or stroke. FIG. 2Dshows an arterial access device or sheath 400 that has a distalocclusion balloon 440 that upon inflation occludes the artery at theposition of the sheath distal tip 406. At any point in a procedure, forexample, during removal of an occlusion by aspiration and/or delivery ofa stentriever or other interventional device, the occlusion balloon 440can be inflated to occlude the vessel to reduce the risk of distalemboli to cerebral vessels. The sheath 400 can include an inflationlumen configured to deliver a fluid for inflation of the occlusionballoon 440 in addition to the working lumen of the sheath 400. Theinflation lumen can fluidly connect the balloon 440, for example, to arm412 on the proximal adaptor. This arm 412 can be attached to aninflation device such as a syringe to inflate the balloon 440 with afluid when vascular occlusion is desired. The arm 412 may be connectedto a passive or active aspiration source to further reduce the risk ofdistal emboli.

According to some implementations, the length of the guide sheath 400 islong enough to access the target anatomy and exit the arterial accesssite with extra length outside of a patient's body for adjustments. Forexample, the guide sheath 400 (whether having a distal occlusion balloon440 or not) can be long enough to access the petrous ICA from thefemoral artery such that an extra length is still available foradjustment. The guide sheath 400 can be a variety of sizes to acceptvarious working devices and can be accommodated to the operator'spreference. For example, current MAT and SMAT techniques describedelivering aspiration catheters having inside diameters of 0.054″-0.072″to an embolus during AIS. Accordingly, the working lumen of the guidesheath 400 can be configured to receive the catheter 200 as well asother catheters or working devices known in the art. For example, theworking lumen can have an inner diameter sized to accommodate at least 6French catheters (1.98 mm or 0.078″ OD), or preferably at least 6.3French catheters (2.079 mm or 0.082″ OD). The inner diameter of theguide sheath 400, however, may be smaller or larger to be compatiblewith other catheter sizes. In some implementations, the working lumencan have an inner diameter sized to accommodate 7 French (2.31 mm or0.091″ OD) catheters or 8 French (2.64 mm or 0.104″ OD) or largercatheters. In some implementations, the working lumen can have an innerdiameter that is at least about 0.054″ up to about 0.070″, 0.071″,0.074″, 0.087″, 0.088″, or 0.100″ and thus, is configured to receive acatheter 200 having an outer diameter that fits snug with thesedimensions. Regardless of the length and inner diameter, the guidesheath 400 is resistant to kinking during distal advancement through thevasculature.

The working lumen included in the sheath 400 can be sized to receive itsrespective working devices in a sliding fit. The working lumen may havean inner diameter that is at least 0.001 inch larger than an outerdiameter of any catheter 200 it is intended to receive, particularly ifthe catheter 200 is to be used for aspiration as will be described inmore detail below. As described in more detail below, the catheter 200can include a slit 236 in the luminal portion 222 configured to widenslightly upon application of suction from an aspiration source andimprove sealing between the catheter 200 and the guide sheath 400.Additionally or alternatively, the distal tip 406 of the sheath 400 canbe designed to move downward onto the outer diameter of the catheter 200to improve sealing, as described above. The strength of the sealachieved allows for a continuous aspiration lumen from the distal tip ofthe catheter 200 to a proximal end 403 of the guide sheath 400 where itis connected to an aspiration source, even in the presence of lowersuction forces with minimal to no leakage. Generally, when there isenough overlap between the catheter 200 and the guide sheath 400 thereis no substantial leakage. However, when trying to reach distal anatomy,the catheter 200 may be advanced to its limit and the overlap betweenthe catheter 200 and the guide sheath 400 is minimal. Thus, additionalsealing can be desirable to prevent leakage around the catheter 200 intothe sheath 400. The sealing between the catheter 200 and the guidesheath 400 can prevent this leakage upon maximal extension of catheter200 relative to sheath 400.

Distal Access Catheter

Again with respect to FIGS. 2A-2B and also FIGS. 3, and 8A-8C, thedistal access system 100 can include a distal access or support catheter200 configured to extend through and out the distal end of the guidesheath 400. FIG. 3 illustrates a side elevational view of animplementation of the catheter 200. The catheter 200 can include arelatively flexible, distal luminal portion 222 coupled to a more rigid,kink-resistant proximal extension 230. The catheter 200 provides a quickway to access stroke locations with simplicity even through the extremetortuosity of the cerebral vasculature. The catheters described hereinhave a degree of flexibility and deliverability that makes themoptimally suitable to be advanced through the cerebral vascular anatomywithout kinking or ovalizing even when navigating hairpin turns. Forexample, the distal luminal portion 222 can perform a 180 degree turn(see turn T shown in FIG. 1B near the carotid siphon) and maintain afolded width across of 4.0 mm without kinking or ovalizing. Further, thedistal luminal portion 222 has a degree of flexibility that maintainsthe natural tortuosity of the vessels through which it is advancedwithout applying straightening forces such that the natural shape andcurvature of the anatomy is maintained during use. The catheter 200,particularly in combination with a catheter advancement element 300,which will be described in more detail below, provides an extendedconduit beyond the guide sheath 400 having exceptional deliverabilitythrough convoluted anatomy that allows for delivering aspirationalforces to a target stroke site as well as for the delivery of strokeinterventional devices such as a stent retriever, stent, flow diverteror other working devices.

An inner lumen 223 extends through the luminal portion 222 between aproximal end and a distal end of the luminal portion 222. The innerlumen 223 of the catheter 200 can have a first inner diameter and theworking lumen of the guide sheath 400 can have a second, larger innerdiameter. Upon insertion of the catheter 200 through the working lumenof the sheath 400, the lumen 223 of the catheter 200 can be configuredto be fluidly connected and contiguous with the working lumen of thesheath 400 such that fluid flow into and/or out of the system 100 ispossible, such as by applying suction from an aspiration source coupledto the system 100 at a proximal end. The combination of sheath 400 andcatheter 200 can be continuously in communication with the bloodstreamduring aspiration at the proximal end with advancement and withdrawal ofcatheter 200.

The spined catheter system can create advantages for distal access overconventional catheters particularly in terms of aspiration. The stepchange in the internal diameter of the catheter column creates a greatadvantage in aspiration flow and force that can be generated by thespined catheter 200 in combination with the conventional guide catheter.For example, where a spined catheter 200 with a 0.070″ internal diameteris paired with a standard 6F outer diameter/0.088″ internal diameterguide catheter (e.g. Penumbra Neuron MAX 088) can create aspirationphysics where the 0.088″ catheter diameter will predominate and create a0.080 equivalent flow in the entire system.

In addition to aspiration procedures, the catheter 200 and distal accesssystem 100 can be used for delivery of tools and interventional workingdevices. As will be described in more detail below, a typical stentretriever to be delivered through the catheter 200 can have a push wirecontrol element of 180 cm. The distal access system 100 having a spinedsupport catheter 200 allows for reaching distal stroke sites using muchshorter lengths (e.g. 120 cm-150 cm). The overall length can be asimportant as diameter and radius on aspiration through the catheter. Theshorter lengths in combination with the elimination of the multiple RHVstypical in tri-axial systems allows for a single-operator use.

It should be appreciated that where the catheter is described herein asan aspiration catheter it should not be limited to only aspiration.Similarly, where the catheter is described herein as a way to deliver astent retriever or other working device it should not be limited assuch. It should also be appreciated that the systems described hereincan be used to perform procedures that incorporate a combination oftreatments. For example, the catheter 200 can be used for the deliveryof a stent retriever delivery system, optionally in the presence ofaspiration through the catheter 200. As another example, a user maystart out performing a first interventional procedure using the systemsdescribed herein, such as aspiration thrombectomy, and switch to anotherinterventional procedure, such as delivery of a stent retriever orimplant.

It should also be appreciated that the catheter 200 need not be spinedor include the proximal extension 230 and instead can be a non-spined,conventional catheter having a uniform diameter. The terms “supportcatheter”, “spined catheter”, “distal access catheter”, and“intermediate catheter” may be used interchangeably herein.

It is desirable to have a catheter 200 having an inner diameter that isas large as possible that can be navigated safely to the site of theocclusion, in order to optimize the aspiration force in the case ofaspiration and/or provide ample clearance for delivery of a workingdevice. A suitable size for the inner diameter of the distal luminalportion 222 may range between 0.040″ and 0.100″, or more preferablybetween 0.054″ and 0.088″, depending on the patient anatomy and the clotsize and composition. The outer diameter of the distal luminal portion222 can be sized for navigation into cerebral arteries, for example, atthe level of the M1 segment or M2 segment of the cerebral vessels. Theouter diameter (OD) should be as small as possible while stillmaintaining the mechanical integrity of the catheter 200. In animplementation, the difference between the OD of distal luminal portion222 of the catheter 200 and the inner diameter of the working lumen ofthe guide sheath 400 is between 0.001″ and 0.002″. In anotherimplementation, the difference is between 0.001″ and 0.004″.

In some implementations, the distal luminal portion 222 of the catheter200 has an outer diameter (OD) configured to fit through a 6F introducersheath (0.070″-0.071″) and the lumen 223 has an inner diameter (ID) thatis sized to receive a 0.054″ catheter. In some implementations, thedistal luminal portion 222 of the catheter 200 has an OD configured tofit through an 8F introducer sheath (0.088″) and the lumen 223 has an IDthat is sized to receive a 0.070″ or 0.071″ catheter. In someimplementations, the OD of the distal luminal portion 222 is 2.1 mm andthe lumen 223 has an ID that is 0.071″. In some implementations, thelumen 223 has an ID that is 0.070″ to 0.073″. The outer diameter of theguide sheath 400 can be suitable for insertion into at least the carotidartery, with a working lumen suitably sized for providing a passagewayfor the catheter 200 to treat an occlusion distal to the carotid arterytowards the brain. In some implementations, the ID of the working lumencan be about 0.074″ and the OD of the body of the guide sheath 400 canbe about 0.090″, corresponding to a 5 French sheath size. In someimplementations, the ID of the working lumen can be about 0.087″ and theOD of the body of the guide sheath 400 can be about 0.104″,corresponding to a 6 French sheath size. In some implementations, the IDof the working lumen can be about 0.100″ and the OD of the body of theguide sheath 400 can be about 0.117″, corresponding to a 7 French sheathsize. In some implementations, the guide sheath 400 ID is between 0.087″and 0.088″ and the OD of the distal luminal portion 222 of the catheter200 is approximately 0.082″ and 0.086″ such that the difference indiameters is between 0.001″ and 0.005″.

In an implementation, the luminal portion 222 of the catheter 200 has auniform diameter from a proximal end to a distal end. In otherimplementations, the luminal portion 222 of the catheter 200 is taperedand/or has a step-down towards the distal end of the distal luminalportion 222 such that the distal-most end of the catheter 200 has asmaller outer diameter compared to a more proximal region of thecatheter 200, for example, near where the distal luminal portion 222seals with the guide sheath 400. In another implementation, the luminalportion 222 of the catheter OD steps up at or near an overlap portion tomore closely match the sheath inner diameter as will be described inmore detail below. It should be appreciated that this step-up in outerdiameter can be due to varying the wall thickness of the catheter 200.For example, the catheter 200 can have a wall thickness that is slightlythicker near the proximal end to provide better sealing with the sheathcompared to a wall thickness of the catheter 200 near the distal end.This implementation is especially useful in a system with more than onecatheter suitable for use with a single access sheath size. It should beappreciated that smaller or larger sheath sizes are considered herein.

The length of the luminal portion 222 can be shorter than a length ofthe working lumen of the guide sheath 400 such that upon advancement ofthe luminal portion 222 towards the target location results in a shortoverlap region 348 between the luminal portion 222 and the working lumenremains (see FIG. 2B). Taking into account the variation in occlusionsites and sites where the guide sheath 400 distal tip 406 may bepositioned, the length of the luminal portion 222 may range from about10 cm to about 45 cm. In some implementations, the distal luminalportion 222 of the catheter 200 can be between 20-45 cm and the proximalextension 230 of the catheter 200 can be between about 90 cm to about100 cm such that the catheter 200 can have a total working length thatis approximately 115 cm. The body 402 of the guide sheath 400 can bebetween 80 cm to about 90 cm. In other implementations, the workinglength of the catheter 200 between a proximal end of the catheter to adistal end of the catheter can be greater than 115 cm up to about 130cm. In some implementations, the catheter 200 can have a working lengthof 133 cm between a proximal tab 234 (or proximal hub) and the distaltip, the distal luminal portion 222 can have a shaft length of about38.7 mm.

The length of the luminal portion 222 can be less than the length of thebody 402 of the guide sheath 400 such that as the catheter 200 isextended from the working lumen there remains a seal between the overlapregion 348 of the catheter 200 and the inner diameter of the workinglumen. In some implementations, the length of the luminal portion 222 issufficient to reach a region of the M1 segment of the middle cerebralartery (MCA) and other major vessels from a region of the internalcarotid artery such that the proximal end region of the luminal portion222 of the catheter 200 avoids extending within the aortic arch. Thislimits the number of severe angulations the luminal portion 222 of thecatheter 200 must navigate while still reaching target sites in the moredistal cerebral anatomy. Used in conjunction with a guide sheath 400having a sheath body 402 and a working lumen, in an implementation wherethe catheter 200 reaches the ICA and the distance to embolus can be lessthan 20 cm.

The distal luminal portion 222 having a length that is less than 30 cm,for example approximately 10 cm to 30 cm, such as 25 cm can allow for anoverlap region 348 with the body 402 to create a seal while stillprovide sufficient reach to intracranial vessels. As described above,the carotid siphon CS is an S-shaped part of the terminal ICA beginningat the posterior bend of the cavernous ICA and ending at the ICAbifurcation into the anterior cerebral artery ACA and middle cerebralartery MCA. In some implementations, the distal luminal portion 222 canbe between about 35 cm-60 cm, or between 40 cm-60 cm, or between 40cm-45 cm long to allow for the distal end of the catheter 200 to extendinto at least the middle cerebral arteries while the proximal extension230 remains proximal to the carotid siphon, as will be described in moredetail below.

The distal luminal portion 222 can have a length measured from its pointof attachment to the proximal extension 230 that is long enough toextend from a region of the internal carotid artery (ICA) that isproximal to the carotid siphon to a region of the ICA that is distal tothe carotid siphon, including at least the M1 region of the brain. Theoverlap region 348 can be maintained between the working lumen of theguide sheath 400 near a distal end region of the sheath body 402 and theluminal portion 222 of the catheter 200 upon extension of the luminalportion 222 into the target anatomy. It should be appreciated where theOD of the catheter 200 along at least a portion of the distal luminalportion 222 substantially matches the inner diameter of the guide sheath400 or the difference can be between 0.001″-0.002″, a seal to fluidbeing injected or aspirated can be achieved by the overlap region 348.The difference between the catheter OD and the inner diameter of theguide sheath 400 can vary, for example, between 1-2 thousandths of aninch, or between 1-4 thousandths of an inch, or between 1-12 thousandthsof an inch. A seal to fluid being injected or aspirated between thecatheter and the sheath can be achieved by the overlap 348 between theirsubstantially similar dimensions without incorporating any separatesealing structure or seal feature.

The overlap region 348 can have a length of a few centimeters and mayvary depending on the distance from the embolus to the distal end of thedistal luminal portion 222, e.g., depending on how far the catheter 200is advanced relative to the guide sheath 400. The overlap region 348 issized and configured to create a seal that allows for a continuousaspiration lumen from the distal tip region of the catheter 200 to aproximal end region 403 of the guide sheath 400 where it can beconnected to an aspiration source. The strength of the seal achieved canbe a function of the difference between the outer diameter of thecatheter 200 and the inner diameter of the working lumen as well as thelength of the overlap region 348, the force of the suction applied, andthe materials of the components. For example, the sealing can beimproved by increasing the length of the overlap region 348. However,increasing the length of the overlap region 348 can result in a greaterlength through which aspiration is pulled through the smaller diameterof the luminal portion 222 rather than the larger diameter of theworking lumen. As another example, higher suction forces applied by theaspiration source can create a stronger seal between the luminal portion222 and the working lumen even in the presence of a shorter overlapregion 348. Further, a relatively softer material forming the luminalportion and/or the body 402 can still provide a sufficient seal even ifthe suction forces are less and the overlap region 348 is shorter. In animplementation, the overlap region 348 is configured to enable sealingagainst a vacuum of up to 28 inHg. In an implementation, the overlapregion 348 is configured to enable sealing against a pressure of up to300 mmHg or up to 600 mmHg or up to 700 mmHg with minimal to no leakage.

The catheter 200 can telescope up such that the distal end of the distalluminal portion 222 can reach cerebrovascular targets within, forexample, the M1, M2 regions while the proximal end of the distal luminalportion 222 remains within the aorta. FIG. 2C illustrates the aorticarch 905. The distal-most carotid from a femoral access point is theright common carotid 906, which takes off from the brachiocephalic trunk910 (or the left common carotid, which takes off from the samebrachiocephalic trunk 910 in so-called “bovine anatomy”). The distalluminal portion 222 is configured to extend down to the level of theaortic arch 905, or below the takeoff of the brachiocephalic trunk 910.This avoids the proximal extension 230 from taking the turn of thebrachiocephalic take-off, which can often be very severe. The takeoff ofthe brachiocephalic is often the first severe turn catheters are likelyto traverse as they ascend to the brain. The less flexible portions ofthe catheter segment are able to avoid these increased tortuosityregions seen at the level of the internal carotid artery. The moreproximal regions of the distal luminal portion 222 are generallydesigned to approach the flexibility of the stiffer proximal extension230 to avoid kinks. These stiffer proximal regions, including thematerial transition between the distal luminal portion 222 at theproximal extension 230, can remain below the level of tortuosity of thebrachiocephalic turn.

In some implementations, the distal luminal portion 222 can have alength that allows the distal end of the distal luminal portion 222 toreach distal to the carotid siphon into the cerebral portion of theinternal carotid artery while at the same time the proximal end of thedistal luminal portion 222 (e.g. where it transitions to the proximalextension 230 as will be described in more detail below) remains withinthe aorta proximal to the take-off of the brachiocephalic trunk 910, forexample within the descending aorta 915 (see FIG. 2C). In thisimplementation, the distal luminal portion can be between about 35 cmand 60 cm.

As mentioned, the point of attachment between the proximal extension 230and the distal luminal portion 222 creates a transition in material andflexibility that can be prone to kinking. Thus, it is preferable toavoid advancing the point of attachment into extreme curvatures. Forexample, the distal luminal portion 222 can have a length that allowsthe point of attachment to be advanced no further than the first turn ofthe carotid siphon, or no further than the brachiocephalic arterytake-off 610, or the aortic arch 905. In some implementations, thedistal luminal portion 222 has a length sufficient to allow the point ofattachment to remain within the descending aorta 915 while stillaccessing M1 or M2 regions of the neurovasculature. Locating thematerial transition within the extreme turn of the brachiocephalictake-off 910 from the aortic arch 905 is generally avoided when thedistal luminal portion 222 has a length that is between about 35 cm toabout 60 cm.

As described above, a seal can be created at the overlap region 348between the distal luminal portion 222 and the sheath body 402. It canbe generally desirable to position the sealing overlap region 348outside of extreme curvatures of the neurovasculature. In someimplementations, the distal luminal portion 222 can have a length thatallows for the distal end of the distal luminal portion 222 to extenddistal to the carotid siphon into the cerebral portion of the internalcarotid artery while at the same time the overlap region 348 remainproximal to the brachiocephalic takeoff 910, the aortic arch 905, orwithin the descending aorta 915. In this implementation, the length canbe between about 35 cm to about 60 cm, about 40 cm to about 60 cm, orgreater than 40 cm up to less than the working length of the sheath body402.

As described above with respect to FIG. 2C, the unreinforced region 407of the distal tip 406 of the sheath 400 can have a length that allows itto provide sufficient sealing force onto the outer surface of thecatheter 200 upon application of a negative pressure. The distal luminalportion 222 of the catheter 200 used with this implementation of sheath400 can have a length that is shorter than 60 cm, shorter than 50 cm,shorter than 40 cm, shorter than 35 cm, shorter than 30 cm to about 10cm. For example, the distal luminal portion 222 of the catheter 200 whenused with a sheath 400 having an unreinforced region 407 configured forsealing can be less than about 30 cm, for example, between 10 cm andabout 30 cm.

It should be appreciated that sealing at the overlap region 348 can bedue to the small difference in inner and outer diameters and/or can bedue to an additional sealing element positioned on an external surfaceof the distal luminal portion or an inner surface of the sheath body. Asealing element can include a stepped up diameter or protruding featurein the overlap region. The sealing element can include one or moreexternal ridge features. The one or more ridge features can becompressible when the luminal portion is inserted into the lumen of thesheath body. The ridge geometry can be such that the sealing elementbehaves as an O-ring, quad ring, or other piston seal design. Thesealing element can include one or more inclined surfaces biased againstan inner surface of the sheath body lumen. The sealing element caninclude one or more expandable members actuated to seal. The inflatableor expandable member can be a balloon or covered braid structure thatcan be inflated or expanded and provide sealing between the two devicesat any time, including after the catheter is positioned at the desiredsite. Thus, no sealing force need be exerted on the catheter duringpositioning, but rather applied or actuated to seal after the catheteris positioned. The sealing element can be positioned on the externalsurface of the distal luminal portion, for example, near the proximalend region of the distal luminal portion and may be located within theoverlap region. More than a single sealing element can be positioned ona length of the catheter.

In some implementations, the additional sealing element can be a cupseal, a balloon seal, or a disc seal formed of a soft polymer positionedaround the exterior of the distal luminal portion near the overlapregion to provide additional sealing. The sealing element can be athin-wall tubing with an outer diameter that substantially matches theinner diameter of the sheath body lumen. The tubing can be sealed on oneend to create a cup seal or on both ends to create a disc or balloonseal. The balloon seal can include trapped air that creates acollapsible space. One or more slits can be formed through the walltubing such that the balloon seal can be collapsible and more easilypassed through an RHV. The balloon seal need not include slits for aless collapsible sealing element that maintains the trapped air. Thesealing element can be tunable for sheath fit and collapse achieved.

In some implementations, the system can include one or more featuresthat restrict extension of the catheter 200 relative to the sheath 400to a particular distance such that the overlap region 348 achieved isoptimum and/or the catheter 200 is prevented from being over-inserted.For example, a tab can be positioned on a region of the catheter 200such that upon insertion of the catheter 200 through the sheath 400 aselected distance, the tab has a size configured to abut against theport through which the catheter 200 is inserted to prevent furtherdistal extension of the catheter 200 through the sheath 400. A tab canalso be positioned on a region of the catheter advancement element 300to ensure optimum extension of the catheter advancement element 300relative to the distal end of the catheter 200 to aid in advancement ofthe catheter 200 into the intracranial vessels.

Again with respect to FIG. 3, the proximal extension 230 is configuredto move the distal luminal portion 222 in a bidirectional manner throughthe working lumen of the guide sheath 400 such that the distal luminalportion 222 can be advanced out of the guide sheath 400 into a targetlocation for treatment within the target vessel. In some implementationsand as shown in FIG. 3, the proximal extension 230 of the catheter 200can have a smaller outer diameter than the outer diameter of the distalluminal portion 222 forming a proximal spine or tether to the catheter200. A smaller outer diameter for the proximal extension 230 than theouter diameter of the distal luminal portion 222 allows for the largerdiameter working lumen of the sheath 400 to maintain greater aspirationforces than would otherwise be provided by the smaller diameter luminalportion 222 of the catheter 200 or allow for the delivery of workingdevices through the lumen with less frictional forces. The markedlyshorter length of the luminal portion 222 results in a step up inluminal diameter between the luminal portion 222 contiguous with theworking lumen providing a markedly increased radius and luminal area fordelivery of a working device and/or aspiration of the clot, particularlyin comparison to other systems where the aspiration lumen runs along theentire inner diameter of the aspiration catheter. More particularly, thecombined volume of the luminal area of the catheter 200 and the luminalarea of the working lumen proximal to the distal luminal portion 222 isgreater than the luminal area of the large bore catheter along theentire length of the system. Thus, the likelihood of removing theembolus during a single aspiration attempt may be increased. Moreparticularly, the stepped up luminal diameter along the proximalextension 230 may enable a greater aspiration force to be achievedresulting in improved aspiration of the embolus. Further, thisconfiguration of the catheter 200 and proximal extension 230 greatlyspeeds up the time required to retract and re-advance the catheter 200and/or working devices through the working lumen out the distal lumen408. This describes the time it takes to aspirate the occlusion. Theproximal extension 230 of the catheter 200 has a length and structurethat extends through the working lumen of the sheath-guide 400 to aproximal end of the system 100 such that the proximal extension 230 canbe used to advance and retract the catheter 200 through the workinglumen. The proximal extension 230 of the catheter 200, however, takes uponly a fraction of the luminal space of the system 100 resulting inincreased luminal area for aspiration and/or delivery of workingdevices. The stepped up luminal diameter also increases the annular areaavailable for forward flushing of contrast, saline, or other solutionswhile devices such as microcatheters or other devices may be coaxiallypositioned in the luminal portion 222 of the catheter 200 and/or theworking lumen. This can increase the ease and ability to performangiograms during device navigation.

In an implementation, the distal luminal portion 222 of the catheter 200is constructed to be flexible and lubricious, so as to be able to safelynavigate to the target location. The distal luminal portion 222 can bekink resistant and collapse resistant when subjected to high aspirationforces so as to be able to effectively aspirate a clot. The luminalportion 222 can have increasing flexibility towards the distal end withsmooth material transitions along its length to prevent any kinks,angulations or sharp bends in its structure, for example, duringnavigation of severe angulations such as those having 90° or greater to180° turns, for example at the aorto-iliac junction, the left subclaviantake-off from the aorta, the takeoff of the brachiocephalic (innominate)artery from the ascending aorta and many other peripheral locations justas in the carotid siphon. The distal luminal portion 222 can transitionfrom being less flexible near its junction with the proximal extension230 to being more flexible at the distal-most end. The change inflexibility from proximal to distal end of the distal luminal portion222 can be achieved by any of a variety of methods as described herein.For example, a first portion of the distal luminal portion 222 can beformed of a material having a hardness of 72 D along a first length, asecond portion can be formed of a material having a hardness of 55 Dalong a second length, a third portion can be formed of a materialhaving a hardness of 40 D along a third length, a fourth portion can beformed of a material having a hardness of 35 D along a fourth length, afifth portion can be formed of a material having a hardness of 25 Dalong a fifth length, a sixth portion can be formed of a material suchas Tecoflex having a hardness of 85 A along a sixth length, and a finaldistal portion of the catheter can be formed of a material such asTecoflex having a hardness of 80 A. In some implementations, the finaldistal portion of the distal luminal portion 222 of the catheter 200 canbe formed of a material such as Tecothane having a hardness of 62 A thatis matched in hardness to a region of the catheter advancement element300, which will be described in more detail below. Thus, the distalluminal portion 222 transitions from being less flexible near itsjunction with the proximal extension 230 to being more flexible at thedistal-most end where, for example, a distal tip of the catheteradvancement element 300 can extend from. It should be appreciated thatother procedural catheters described herein can have a similarconstruction providing a variable relative stiffness that transitionsfrom the proximal end towards the distal end of the catheter as will bedescribed elsewhere herein.

The distal luminal portion 222 includes two or more layers. In someimplementations, the distal luminal portion 222 includes an innerlubricious liner, a reinforcement layer, and an outer jacket layer, eachof which will be described in more detail.

The lubricious inner liner can be a PTFE liner, with one or morethicknesses along variable sections of flexibility. The PTFE liner canbe a tubular liner formed by dip coating or film-casting a removablemandrel, such as a silver-plated copper wire as is known in the art.Various layers can be applied having different thicknesses. For example,a base layer of etched PTFE can be formed having a thickness of about0.005″. A second, middle layer can be formed over the base layer that isTecoflex SG-80 A having a thickness of about 0.0004″. A third, top layercan be formed over the middle layer that is Tecoflex SG-93 A having athickness of about 0.0001″ or less. A reinforcement layer and/orreinforcement fiber can be applied to the inner liner, followed by theouter jacket layer and/or additional outer coating prior to removing themandrel by axial elongation.

The reinforcement layer is a generally tubular structure formed of, forexample, a wound ribbon or wire coil or braid. The material for thereinforcement structure may be stainless steel, for example 304stainless steel, Nitinol, cobalt chromium alloy, or other metal alloythat provides the desired combination of strengths, flexibility, andresistance to crush. In some implementations, the distal luminal portion222 has a reinforcement structure that is a Nitinol ribbon wrapped intoa coil. For example, the coil reinforcement can be a tapered ribbon ofNitinol set to a particular inner diameter (e.g. 0.078″ to 0.085″ innerdiameter) and having a pitch (e.g. between 0.012″ and 0.016″). Theribbon can be 304 stainless steel (e.g. about 0.012″×0.020″). The coilcan be heat-set prior to transferring the coil onto the catheter. Thepitch of the coil can increase from proximal end towards distal end ofthe distal luminal portion 222. For example, the ribbon coils can havegaps in between them and the size of the gaps can increase movingtowards the distal end of the distal luminal portion 222. For example,the size of the gap between the ribbon coils can be approximately 0.016″gap near the proximal end of the distal luminal portion 222 and the sizeof the gap between the ribbon coils near the distal end can be largersuch as 0.036″ gap. This change in pitch provides for increasingflexibility near the distal-most end of the distal luminal portion 222.The reinforcement structure can include multiple materials and/ordesigns, again to vary the flexibility along the length of the distalluminal portion 222.

The outer jacket layer may be composed of discreet sections of polymerwith different durometers, composition, and/or thickness to vary theflexibility along the length of the distal luminal portion 222 asdescribed above.

At least a portion of the outer surface of the catheter 200 can becoated with a lubricious coating such as a hydrophilic coating. In someimplementations, the coating may be on an inner surface and/or an outersurface to reduce friction during tracking. The coating may include avariety of materials as is known in the art. The proximal extension 230may also be coated to improve tracking through the working lumen.Suitable lubricious polymers are well known in the art and may includesilicone and the like, hydrophilic polymers such as high-densitypolyethylene (HDPE), polytetrafluoroethylene (PTFE), polyarylene oxides,polyvinylpyrolidones, polyvinyl alcohols, hydroxy alkyl cellulosics,algins, saccharides, caprolactones, HYDAK coatings (e.g. B-23K,HydroSleek), and the like, and mixtures and combinations thereof.Hydrophilic polymers may be blended among themselves or with formulatedamounts of water insoluble compounds (including some polymers) to yieldcoatings with suitable lubricity, bonding, and solubility.

In an implementation, the distal-most end of the distal luminal portion222 has a flexural stiffness (E*I) in the range of 1500 to 3000 N-mm²and the remaining portion of the distal luminal portion 222 has a higherflexural stiffness, where E is the elastic modulus and I is the areamoment of inertia of the device. These bending stiffness ranges in N-mm²can be measured by assessing the grams of force generated upondeflecting the device a certain distance using a particular lengthgauge. For example, using a 3 mm length force gauge and deflecting a tipof the catheter 2 mm, 30-60 grams of force can be generated or can rangein bending stiffness between 1500-3000 N-mm². The flexibility of thedistal luminal portion 222 can be based on deflection measurements andthe related calculations. As a comparison, the flexibility of thecatheter advancement element 300 based on similar deflectionmeasurements and calculations can be as follows. Upon 2 mm deflectionand force gauge length of 3 mm, the catheter advancement element 300 canrange in gram-force between 1-5 or can range in bending stiffnessbetween 50-200 N-mm². It should be appreciated that other proceduralcatheters described herein can have a similar flexibility rangesproviding a variable relative stiffness that transitions from theproximal end towards the distal end of the catheter as will be describedelsewhere herein.

Again with respect to FIGS. 2A-2B, the distal luminal portion 222 of thecatheter 200 can have a radiopaque marker 224 a at the distal tip regionto aid in navigation and proper positioning of the tip underfluoroscopy. Additionally, a proximal region of the catheter 200 mayhave one or more proximal radiopaque markers 224 b so that the overlapregion 348 can be visualized as the relationship between a radiopaquemarker 411 on the guide sheath 400 and the radiopaque marker 224 b onthe catheter 200. In an implementation, the two radiopaque markers(marker 224 a at distal tip and a more proximal marker 224 b) aredistinct so as to minimize confusion of the fluoroscopic image, forexample the catheter proximal marker 224 b may be a single band and themarker 411 on the guide sheath 400 may be a double band and any markerson a working device delivered through the distal access system can haveanother type of band or mark. The radiopaque markers 224 of the distalluminal portion 222, particularly those near the distal tip regionnavigating extremely tortuous anatomy, can be relatively flexible suchthat they do not affect the overall flexibility of the distal luminalportion 222 near the distal tip region. The radiopaque markers 224 canbe tungsten-loaded or platinum-loaded markers that are relativelyflexible compared to other types of radiopaque markers used in deviceswhere flexibility is not paramount. In some implementations, theradiopaque marker can be a band of tungsten-loaded PEBAX having adurometer of 35 D.

As best shown in FIGS. 8B-8C, at least one reinforcement fiber 801 canbe incorporated within a wall of the distal luminal portion 222 toprevent elongation of a coiled reinforcement layer 803. The fiber 801can be positioned between the liner layer 805 and the reinforcementlayer 803. The fiber 801 can extend along the longitudinal axis A of thecatheter 200 from a proximal end region of the distal luminal portion222 to a distal end region of the portion 222. The proximal end of thefiber 801 can be coupled to a region of the distal luminal portion 222near where it couples to the proximal extension 230. A distal end of thefiber 801 can terminate near the distal end of the distal luminalportion 222. The distal end of the fiber 801 can be captured between thedistal marker band 224 a and an end of the reinforcement layer 803. Thedistal marker band 224 a can be fully encapsulated between the innerliner 805 and the outer jacket 807. In some implementations, the distalend of the fiber 801 extends distal to the last coil of thereinforcement layer 803 running under the marker band 224 a and thenlooping around the band 224 a back in a proximal direction. The free endof the fiber 801 is thereby captured under the reinforcement layer 803and the marker band 224 a. The reinforcement fiber 801 thus terminatesat the location the reinforcement layer 803 terminates thereby leaving alength of between about 10 cm-12 cm of the unreinforced distal-most tipregion. The catheter 200 can include a plurality of reinforcement fibers801 extending longitudinally along the distal luminal portion 222, suchas two, three, four, or more fibers 801 distributed around thecircumference of the portion 222 and aligned parallel with one anotherand with the longitudinal axis A of the catheter 200. The material ofthe reinforcement fiber 801 can vary, including but not limited tovarious high tenacity polymers like polyester, PEEK, and other similarmaterials.

As mentioned previously, the proximal extension 230 is configured toallow distal advancement and proximal retraction of the catheter 200through the working lumen of the guide sheath 400 including passage outthe distal lumen 408. In an implementation, the length of the proximalextension 230 is longer than the entire length of the guide sheath 400(from distal tip to proximal valve), such as by about 5 cm to 15 cm. Thelength of the body 402 can be in the range of 80 to 90 cm or up to about100 cm or up to about 105 cm and the length of the proximal extension230 can be between 90-100 cm.

Again with respect to FIG. 3, the proximal extension 230 can include oneor more markers 232 to indicate the overlap between the distal luminalportion 222 of the catheter 200 and the sheath body 402 as well as theoverlap between the distal luminal portion 222 of the catheter 200 andother interventional devices that may extend through the distal luminalportion 222. At least a first mark 232 a can be an RHV proximity markerpositioned so that when the mark 232 a is aligned with the sheathproximal hemostasis valve 434 during insertion of the catheter 200through the guide sheath 400, the catheter 200 is positioned at thedistal-most position with the minimal overlap length needed to createthe seal between the catheter 200 and the working lumen. At least asecond mark 232 b can be a Fluoro-saver marker that can be positioned onthe proximal extension 230 and located a distance away from the distaltip of the distal luminal portion 222. In some implementations, a mark232 can be positioned about 100 cm away from the distal tip of thedistal luminal portion 222.

The proximal extension 230 can include a gripping feature such as a tab234 on the proximal end to make the proximal extension 230 easy to graspand advance or retract. The tab 234 can couple with one or more othercomponents of the system as will be described in more detail below. Theproximal tab 234 can be designed to be easily identifiable amongst anyother devices that may be inserted in the sheath proximal valve 434,such as guidewires or retrievable stent device wires. A portion of theproximal extension 230 and/or tab 234 can be colored a bright color, ormarked with a bright color, to make it easily distinguishable fromguidewire, retrievable stent tethers, or the like. Where multiplecatheters 200 are used together in a nesting fashion to reach moredistal locations within the brain, each proximal extension 230 and/ortab 234 can be color-coded or otherwise labeled to clearly show to anoperator which proximal extension 230 of which catheter 200 it iscoupled to. The proximal portion 366 of the catheter advancement element300 can also include a color to distinguish it from the proximalextension 230 of the catheter 200.

The tab 234 can be integrated with or in addition to a proximal hubcoupled to a proximal end of the proximal extension 230. For example, aswill be described in more detail below, the proximal extension 230 canbe a hypotube having a lumen. The lumen of the hypotube can be in fluidcommunication with the proximal hub at a proximal end of the proximalextension 230 such that aspiration forces and/or fluids can be deliveredthrough the hypotube via the proximal hub.

The proximal extension 230 can be configured with sufficient stiffnessto allow advancement and retraction of the distal luminal portion 222 ofthe catheter 200, yet also be flexible enough to navigate through thecerebral anatomy as needed without kinking. The configuration of theproximal extension 230 can vary. In some implementations, the proximalextension 230 can be a tubular element having an outer diameter that issubstantially identical to the outer diameter of the distal luminalportion 222 similar to a typical catheter device. In otherimplementations, the outer diameter of the proximal extension 230 issized to avoid taking up too much luminal area in the lumen of the guidesheath 400 as described above.

The proximal extension 230 can be a solid metal wire that is round,rectangular, trapezoid, D-shape, or oval cross-sectional shape (seeFIGS. 4A-4G). The proximal extension 230 can be a flattened ribbon ofwire having a rectangular cross-sectional shape as shown in FIG. 4A. Theflattened ribbon of wire can also have square, rectangular, or othercross-sectional shape. The ribbon of wire can be curved into a circular,oval, c-shape, or quarter circle or other cross-sectional area along anarc. As such, an inner-facing surface of the ribbon can be substantiallyflat and an outer-facing surface of the ribbon (i.e. the surfaceconfigured to abut against an inner diameter of the access sheaththrough which it extends) can be substantially curved (see FIGS. 4F-4G).The curvature of the surface can substantially match the curvature ofthe inner surface of the access sheath. The resulting cross-sectionalshape of such a ribbon can be generally trapezoidal. The overalldimensions of the ribbon can vary depending on its cross-sectional shapeand the size of the distal luminal portion. The 0.054″ sized catheter200 can have a proximal extension 230 that is trapezoidal or D-shaped incross-section. The inner-facing, flat surface can have a width that isapproximately 0.020″ wide and in the case of the trapezoidal-shapedimplementation, the outer-facing, curved surface can extend along an arcthat is approximately 0.030″ long. The 0.070″ sized catheter 200 canhave a proximal extension that is trapezoidal or D-shaped incross-section, and the width of the inner-facing, flat surface isslightly greater, for example, approximately 0.025″ and in the case ofthe trapezoidal-shaped implementation, the outer-facing, curved surfacecan extend along an arc that is approximately 0.040″ long. The 0.088″sized catheter 200 can have a proximal extension that is trapezoidal orD-shaped in cross-section, and the width of the inner-facing, flatsurface is approximately 0.035″ and the outer-facing, curved surface ofthe trapezoidal-shaped implementation can extend along an arc that isapproximately 0.050″ long.

The proximal extension 230 can be a hollow wire having a lumen 235extending through it, such as a hypotube as shown in FIG. 4B. Thehypotube can have an oval or circular shape. In an implementation, theproximal extension 230 is a ribbon of stainless steel having dimensionsof about 0.012″×0.020″. In an implementation, the proximal extension 230is a ribbon of stainless steel having dimensions of about 0.014″×0.020″.In an implementation, the proximal extension 230 is a round wire, withdimensions from 0.014″ to 0.018″. In another implementation, theproximal extension 230 is a ribbon with dimensions ranging from 0.010″to 0.015″ thick, and 0.015″ thick to 0.025″ thick. In an implementation,the proximal extension 230 is a hypotube formed from a flattened ribbonof stiff material rolled into a tubular shape to have a lumen 235. Insome implementations, the proximal extension 230 can be formed of aflattened ribbon of stainless steel and rolled into a hypotube such thatthe proximal extension 230 has a wall thickness of about 0.007″, aninner diameter of about 0.004″ and an outer diameter of about 0.018″before the hypotube is modified into an oval cross-sectional shape. Theovalized hypotube can maintain an inner diameter that is at least 0.001″along at least a first dimension and an outer diameter that is at least0.015″ along at least a first dimension. In an implementation, theproximal extension 230 material is a metal such as a stainless steel orNitinol as well as a plastic such as any of a variety of polymers. In animplementation, the proximal extension 230 is a stainless steel hypotubehaving an oval cross-sectional shape (see FIG. 4B). The oval tubularshape can increase the column strength, pushability and kink resistanceof the proximal extension 230 for improved advancement through tortuousanatomy. The cross-sectional area of an oval hypotube minimizes theimpact of the catheter 200 on movement of other tools through theworking lumen of the sheath 400. FIG. 4C illustrates a cross-sectionalview of the working lumen of the sheath 400 having a proximal portion230 extending therethrough. The proximal portion 230 has a rectangularcross-sectional shape. FIG. 4D illustrates a cross-sectional view of theworking lumen having an ovalized hypotube proximal portion 230 and acatheter advancement element 300 extending therethrough. FIG. 4Eillustrates the comparison of surface area between therectangular-shaped ribbon and the oval hypotube. The oval hypotube hasless surface area compared to the rectangular-shaped ribbon allowing fora greater flow rate through the working lumen, for example, duringapplication of aspirating forces. The materials, dimensions, and shapeof the proximal extension 230 can be selected based on the materials,dimensions, and shape of the distal luminal portion 222. For example,the proximal extension 230 can be a rectangular ribbon of 340 stainlesssteel that is 0.012″×0.020″ and the distal luminal portion 222 can havean inner diameter of about 0.054″ to about 0.072″. In a furtherimplementation, the proximal extension 230 can be a rectangular ribbonof 340 stainless steel that is 0.014″×0.020″ and the distal luminalportion 222 can have an inner diameter of about 0.088″. The additionalheft of the stainless steel ribbon 230 can be useful in advancing alarger inner diameter catheter without kinking.

Now with respect to FIGS. 5A-5F, the junction between the distal luminalportion 222 of the catheter 200 and the proximal extension 230 can beconfigured to allow a smooth transition of flexibility between the twoportions so as not to create a kink or weak point. The smooth transitionat the joint between the distal luminal portion 222 and the proximalextension 230 also allows for smooth passage of devices through thecontiguous inner lumen created by the working lumen of the guide sheath400 and the lumen 223 of the luminal portion 222 of the catheter 200. Inan implementation, the distal luminal portion 222 has a transitionsection 226 near where the luminal portion 222 couples to the proximalextension 230 (see FIG. 5A). The transition section 226 can have anangled cut such that there is no abrupt step transition from the workinglumen of the guide sheath 400 to the inner lumen 223 of the catheter200. The angled cut can be generally planer. In an alternateimplementation, the angled cut is curved or stepped to provide a moregradual transition zone. It should be appreciated that the proximal endregion of the distal luminal portion 222 can be angled in an obliquemanner relative to a longitudinal axis of the catheter 200 such that theproximal end and proximal opening into the lumen are at an angle otherthan 90° to the longitudinal axis of the catheter 200, for examplebetween approximately 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, or 45°up to less than 90°. The proximal end region of the distal luminalportion 222 can also be aligned substantially perpendicular to thelongitudinal axis of the catheter 200 such that the proximal end andproximal opening into the lumen are substantially 90° to thelongitudinal axis of the catheter 200. Similarly, the distal end regionof the distal luminal portion 222 can be angled in an oblique mannerrelative to a longitudinal axis of the catheter 200 such that the distalend and distal opening from the lumen 223 are at an angle other than 90°to the longitudinal axis of the catheter 200, for example betweenapproximately 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, or 45° up toless than 90°. The distal end region of the distal luminal portion 222can also be aligned substantially perpendicular to the longitudinal axisof the catheter 200 such that the distal end and distal opening into thelumen are substantially 90° to the longitudinal axis of the catheter200.

The proximal extension 230 can be coupled to a proximal end region ofthe catheter 200 and/or may extend along at least a portion of thedistal luminal portion 222 such that the proximal extension 230 couplesto the distal luminal portion 222 a distance away from the proximal end.The proximal extension 230 can be coupled to the distal luminal portion222 by a variety of mechanisms including bonding, welding, gluing,sandwiching, stringing, tethering, or tying one or more componentsmaking up the proximal extension 230 and/or portion 222. The distalluminal portion 222 and the proximal extension 230 may be joined by aweld bond, a mechanical bond, an adhesive bond, or some combinationthereof. In some implementations, the proximal extension 230 and luminalportion 222 are coupled together by sandwiching the proximal extension230 between layers of the distal luminal portion 222. For example, theproximal extension 230 can be a hypotube or rod having a distal end thatis skived, ground or cut such that the distal end can be laminated orotherwise attached to the layers of the catheter portion 222 near aproximal end region. The region of overlap between the distal end of theproximal extension 230 and the portion 222 can be at least about 1 cm.This type of coupling allows for a smooth and even transition from theproximal extension 230 to the luminal portion 222.

Still with respect to FIGS. 5A-5F, the transition section 226 of thedistal luminal portion 222 can open up into a trough 238 extending alength proximal to the transition section 226. In some implementations,the trough 238 has a cross-sectional geometry that is substantiallycurved. For example, the trough 238 can extend along an arc of thelongitudinal axis of the catheter 200 between about 20 to about 90degrees. In some implementations, the trough 238 is curved to create afunnel-shape and aids in loading and reloading a catheter advancementelement 300 into the lumen of the catheter 200. In otherimplementations, the edges of the trough 238 curve such that the trough238 is not substantially flat. The curved shape can vary including atear-drop shape that allows for a smooth transition and betterloading/reloading of the catheter advancement element 300 into the lumenand avoids flat edges that can abut and catch the component as it isinserted. In other implementations, the trough 238 is substantiallyflat. The trough 238 can provide a smooth transition between distalluminal portion 222 and proximal extension 230 when the device is forcedto bend. This can reduce the likelihood of kinking and facilitatepushing against resistance.

A proximal region of the distal luminal portion 222 can incorporate oneor more markers to provide visualization under fluoro duringloading/reloading of the catheter advancement element 300. For example,the proximal end region can include a region of Pebax (e.g. 35 D) loadedwith tungsten (80%) for radiopacity.

The distal end of the proximal extension 230 and/or the distal luminalportion 222 may have features that facilitate a mechanical joint duringa weld, such as a textured surface, protruding features, or cut-outfeatures. During a heat weld process, the features would facilitate amechanical bond between the polymer distal luminal portion 222 and theproximal extension 230. For example, as shown in FIGS. 6A-6F theproximal end of the distal luminal portion 222 can include a shortmating sleeve 240 coupled to a proximal edge 221 of the distal luminalportion 222. The sleeve 240 can include an inner lumen extending betweena proximal opening 242 and a distal opening 241. The distal end of theproximal extension 230 can insert through the proximal opening 242 andwithin the inner lumen of the sleeve 240 to couple the proximalextension 230 to the distal luminal portion 222. In someimplementations, the proximal extension 230 can couple with the distalluminal portion 222 such that a distal opening 231 of the hypotubeforming the proximal extension 230 can communicate with the lumen 223 ofthe distal luminal portion 222, for example, through the distal opening241 of the sleeve 240. The sleeve 240 can also provide transitionbetween distal luminal portion 222 and proximal extension 230 similar tothe trough 238. The distal luminal portion 222 need not include a matingsleeve 240 to couple with the proximal extension 230. For example, thedistal end of the proximal extension 230 can insert through a wall ofthe trough 238 at the proximal end of the distal luminal portion 222(see FIG. 5A, 5E-5F). The distal end of the proximal extension 230 canextend along the length of the trough 238 and along at least a length ofthe wall of the distal luminal portion 222.

As mentioned above, the luminal portion 222 of the catheter 200 can havea uniform diameter or wall thickness from a proximal end to a distal endor the luminal portion 222 can have different outer diameters or wallthicknesses along its length. For example, the distal-most end of thedistal luminal portion 222 can have a smaller outer diameter compared toa more proximal region of the distal luminal portion 222. FIGS. 5A-5B,5E-5F as well as FIGS. 6A-6B, 6E-6F, and FIG. 8A show a distal luminalportion 222 having a distal tubular region or distal tube 245 having asmaller outer diameter and a proximal tubular region or proximal tube246 have a larger outer diameter. The distal tube 245 transitions via astep-up 247 to the proximal tube 246. As best shown in FIGS. 5A and 6A,the inner diameters of distal tube 245 and the proximal tube 246 aresubstantially the same providing a smooth inner wall surface for thelumen 223. The outer diameter of the distal tube 245 is smaller than theouter diameter of the proximal tube 246. The step-up 247 is formed by atransition in wall thickness between the distal tube 246 and theproximal tube 247. In some implementations, the outer diameter of thedistal tube 246 can be about 0.080″ to about 0.084″ and the outerdiameter of the proximal tube 247 can be about 0.087″ to about 0.088″.

At least a portion of the wall of the larger outer diameter proximaltube 246 can be discontinuous such that it includes a slit 236 (seeFIGS. 5A-5C, 5E-5F, 6A-6C, and 6E-6F). The slit 236 can extend adistance along the length of the proximal tube 246. The slit 236 canextend from an edge 221 of the proximal tube 246 at least about 2 cm ofa length of the proximal tube 247. The slit 236 can, but need not,extend along the entire length of the proximal tube 247 to the locationof the step-up 247. Additionally, the proximal tube 247 can include morethan one slit 236. The slit 236 can be positioned in the larger diameterproximal tube 246 at a location opposite from where the distal end ofthe proximal extension 230 couples with the wall of the distal luminalportion 222. As such that distal end of the proximal extension 230embedded within the wall of the proximal tube 246 lies opposite the slit236 (see FIGS. 5C and 6C). It should be appreciated that the slit 236can be positioned around the proximal tube 246 at another location.

The slit 236 can allow for the proximal tube 246 to expand slightly suchthat the ends of the wall forming the slit 236 separate forming a gaptherebetween. For example, upon insertion of the catheter 200 throughthe working lumen of the sheath 400, the outer diameter can be receivedin a sliding fit such that at least an overlap region 348 remains. Uponapplication of an aspirational force through the working lumen, forexample, by applying suction from an aspiration source coupled to theproximal end 403 of the guide sheath 400, the sealing provided at theoverlap region 348 can be enhanced by a slight widening of the gapformed by the slit 236. This slight expansion provides for bettersealing between the outer diameter of the proximal tube 246 and theinner diameter of the working lumen of the sheath 400 because the outersurface of the walls of the catheter 200 can press against the innersurface of the working lumen creating a tight fit between the catheter200 and the sheath 400. This improved sealing between the outer surfaceof the catheter 200 and the inner surface of the working lumen minimizesthe seepage of blood from the vessel into the working lumen directlythrough the distal opening 408. Thus, the larger outer diameter of theproximal tube 246 in combination with the slit 236 can enhance sealingbetween the catheter 200 and the sheath 400 by accommodating forvariations of sheath inner diameters. The slit 236 can effectivelyincrease the outer diameter of the proximal tube 246 depending onwhether the walls forming the slit 236 are separated a distance. Thewalls forming the slit 236 can separate away from one another andincrease a width of slit. The outer diameter of the proximal tube 246including the increased width upon separation of the walls forming theslit 236 can be the same size or larger than the inner diameter of thesheath through which the proximal tube 246 is inserted. This allows fora single catheter to be compatible with a larger range of innerdiameters. In some implementations, the outer diameter of the proximaltube 246 can be 0.081″ when the walls forming the slit 236 abut oneanother and no gap is present. The outer diameter of the proximal tube246 can increase up to about 0.087″ when the walls forming the slit 236are separated a maximum distance away from one another. Additionally,the increased wall thickness of the proximal tube 246 allows forcreating a more robust joint between the distal luminal portion 222 andthe proximal extension 230 of the catheter.

Additionally or alternatively, the distal tip 406 of the sheath 400 caninclude one or more features that improve sealing between the innerdiameter of the working lumen of the sheath 400 and the outer diameterof the proximal end region of the catheter 200, as described elsewhereherein.

Catheter Advancement Element

As mentioned above, the distal access system 100 can, but need not,include a catheter advancement element 300 for delivery of the catheter200 to the distal anatomy. It should be appreciated that where thecatheter 200 is described herein as being used together or advanced withthe catheter advancement element 300 that the catheter advancementelement 300 need not be used to deliver the catheter 200 to a targetlocation. For example, other advancement tools are to be consideredherein, such as a microcatheter and/or guidewire as is known in the art.Similarly, the catheter advancement element 300 can be used together toadvance other catheters besides the catheter 200 described herein. Forexample, the catheter advancement element 300 can be used to deliver a5MAX Reperfusion Catheter (Penumbra, Inc. Alameda, Calif.) for clotremoval in patients with acute ischemic stroke or other reperfusioncatheters known in the art. Although the catheter advancement element300 is described herein in reference to catheter 200 it should beappreciated that it can be used to advance other catheters and it is notintended to be limiting to its use.

As described above, the distal access system 100 is capable of providingquick and simple access to distal target anatomy, particularly thetortuous anatomy of the cerebral vasculature. The flexibility anddeliverability of the distal access catheter 200 allow the catheter 200to take the shape of the tortuous anatomy and avoids exertingstraightening forces creating new anatomy. The distal access catheter200 is capable of this even in the presence of the catheter advancementelement 300 extending through its lumen. Thus, the flexibility anddeliverability of the catheter advancement element 300 is on par orbetter than the flexibility and deliverability of the distal luminalportion 222 of the distal access catheter 200 in that both areconfigured to reach the middle cerebral artery (MCA) circulation withoutstraightening out the curves of the anatomy along the way.

The catheter advancement element 300 can include a non-expandable,flexible elongate body 360 coupled to a proximal portion 366. Theelongate body 360 can be received within and extended through theinternal lumen 223 of the distal luminal portion 222 of the catheter 200(see FIG. 2B). A distal tip 346 of the catheter advancement element 300can be extended beyond the distal end of the catheter 200 as shown inFIG. 2B. The proximal portion 366 of the catheter advancement element300 is coupled to a proximal end region of the elongate body 360 andextends proximally therefrom. The proximal portion 366 can be lessflexible than the elongate body 360 and configured for bi-directionalmovement of the elongate body 360 of the catheter advancement element300 within the luminal portion 222 of the catheter 200, as well as formovement of the catheter system 100 as a whole. The elongate body 360can be inserted in a coaxial fashion through the internal lumen 223 ofthe luminal portion 222. The outer diameter of at least a region of theelongate body 360 can be sized to substantially fill the internal lumen223 of the luminal portion 222.

The overall length of the catheter advancement element 300 (e.g. betweenthe proximal end through to the distal-most tip) can vary, but generallyis long enough to extend through the support catheter 200 plus at leasta distance beyond the distal end of the support catheter 200 while atleast a length of the proximal portion 366 remains outside the proximalend of the guide sheath 400. In some implementations, the overall lengthof the catheter advancement element 300 is about 149 cm and a workinglength of 143 cm from a proximal tab or hub to the distal-most tip. Theelongate body 360 can have a length that is at least as long as theluminal portion 222 of the catheter 200 although it should beappreciated the elongate body 360 can be shorter than the luminalportion 222 so long as at least a length remains inside the luminalportion 222 when a distal portion of the elongate body 360 is extendeddistal to the distal end of the luminal portion 222. In someimplementations, the shaft length of the distal luminal portion 222 canbe about 39 cm and the insert length of the elongate body 360 can be atleast about 48.5 cm, 49 cm, or about 49.5 cm. The proximal portion 366can have a length that varies as well. In some implementations, theproximal portion 366 is about 94 cm. The distal portion extending distalto the distal end of the luminal portion 222 can include distal tip 346that protrudes a length beyond the distal end of the luminal portion 222during use of the catheter advancement element 300. The distal tip 346of the elongate body 360 that is configured to protrude distally fromthe distal end of the luminal portion 222 aids in the navigation of thecatheter system through the tortuous anatomy of the cerebral vessels, aswill be described in more detail below. The proximal portion 366 coupledto and extending proximally from the elongate body 360 can aligngenerally side-by-side with the proximal extension 230 of the catheter200. The arrangement between the elongate body 360 and the luminalportion 222 can be maintained during advancement of the catheter 200through the tortuous anatomy to reach the target location for treatmentin the distal vessels and aids in preventing the distal end of thecatheter 200 from catching on tortuous branching vessels, as will bedescribed in more detail below.

In some implementations, the elongate body 360 can have a region ofrelatively uniform outer diameter extending along at least a portion ofits length and the distal tip 346 tapers down from the uniform outerdiameter. When the catheter advancement element 300 is inserted throughthe catheter 200, this tapered distal tip 346 is configured to extendbeyond and protrude out through the distal end of the luminal portion222 whereas the more proximal region of the body 360 having a uniformdiameter remains within the luminal portion 222. As mentioned, thedistal end of the luminal portion 222 can be blunt and have no change inthe dimension of the outer diameter whereas the distal tip 346 can betapered providing an overall elongated tapered geometry of the cathetersystem. The outer diameter of the elongate body 360 also approaches theinner diameter of the luminal portion 222 such that the step up from theelongate body 360 to the outer diameter of the luminal portion 222 isminimized. Minimizing this step up prevents issues with the lip formedby the distal end of the luminal portion 222 catching on the tortuousneurovasculature, such as around the carotid siphon near the ophthalmicartery branch, when the distal tip 346 bends and curves along within thevascular anatomy. In some implementations, the inner diameter of theluminal portion 222 can be 0.054″ and the outer diameter of the elongatebody 360 can be 0.048″ such that the difference between them is about0.006″. In some implementations, the inner diameter of the luminalportion 222 can be 0.070″ and the outer diameter of the elongate body360 can be 0.062″ such that the difference between them is about 0.008″.In some implementations, the inner diameter of the luminal portion 222can be 0.088″ and the outer diameter of the elongate body 360 can be0.080″ such that the difference between them is about 0.008″. In someimplementations, the inner diameter of the luminal portion 222 can be0.072″ and the outer diameter of the elongate body 360 is 0.070″ suchthat the difference between them is about 0.002″. In otherimplementations, the outer diameter of the elongate body 360 is 0.062″such that the difference between them is about 0.010″. Despite the outerdiameter of the elongate body 360 extending through the lumen of theluminal portion 222, the luminal portion 222 and the elongate body 360extending through it in co-axial fashion are flexible enough to navigatethe tortuous anatomy leading to the level of M1 or M2 arteries withoutkinking and without damaging the vessel.

The length of the distal tip 346 (e.g. the region of the catheteradvancement element 300 configured to extend distal to the distal end ofthe catheter 200 during use) can vary. In some implementations, thelength of the distal tip 346 can be in a range of between about 0.50 cmand about 3.0 cm from the distal-most terminus of the elongate body 360.In other implementations, the length of the distal tip 346 is at leastabout 0.8 cm. In other implementations, the length of the distal tip 346is between 2.0 cm to about 2.5 cm. In some implementations, the lengthof the distal tip 236 varies depending on the inner diameter of theelongate body 360. For example, the length of the distal tip 236 can beas short as 0.5 cm and the inner diameter of the catheter 200 can be0.054″. The distal tip 346 can be a constant taper from the outerdiameter of the elongate body 360 down to a second smaller outerdiameter at the distal-most tip. In some implementations, the constanttaper of the distal tip 346 can be from about 0.048″ outer diameter downto about 0.031″ outer diameter. In some implementations, the constanttaper of the distal tip 346 can be from 0.062″ outer diameter to about0.031″ outer diameter. In still further implementations, the constanttaper of the distal tip 346 can be from 0.080″ outer diameter to about0.031″ outer diameter. The length of the constant taper of the distaltip 346 can vary, for example, between 0.8 cm to about 2.5 cm, orbetween 1 cm and 3 cm, or between 2.0 cm and 2.5 cm. The angle of thetaper can vary depending on the outer diameter of the elongate body 360.For example, the taper can be between 0.9 to 1.6 degree angle relativeto horizontal. The taper can be between 2-3 degree angle from a centerline of the elongate body 360.

It should be appreciated that the distal tip 346 need not taper and canachieve its soft, atraumatic and flexible characteristic due to amaterial property other than due to a change in outer dimension tofacilitate endovascular navigation to an embolus in tortuous anatomy.Additionally or alternatively, the distal tip 346 of the elongate body360 can have a transition in flexibility along its length. The mostflexible region of the distal tip 346 can be its distal terminus. Movingalong the length of the distal tip 346 from the distal terminus towardsa region proximal to the distal terminus, the flexibility can graduallyapproach the flexibility of the distal end of the luminal portion 222.For example, the distal tip 346 can be formed of a material having ahardness of no more than 35 D or about 62 A and transitions proximallytowards increasingly harder materials having a hardness of no more than55 D and 72 D up to the proximal portion 366, which can be a stainlesssteel hypotube, or a combination of a material property and taperedshape. The materials used to form the regions of the elongate body 360can include PEBAX (such as PEBAX 25 D, 35 D, 55 D, 72 D) with alubricious additive compound, such as Mobilize (Compounding Solutions,Lewiston, Me.). In some implementations, the material used to form aregion of the elongate body 360 can be Tecothane 62A. Incorporation of alubricious additive directly into the polymer elongate body meansincorporation of a separate lubricious liner, such as a Teflon liner, isunnecessary. This allows for a more flexible element that can navigatethe distal cerebral anatomy and is less likely to kink. Similarmaterials can be used for forming the distal luminal portion 222 of thecatheter 200 providing similar advantages. It should also be appreciatedthat the flexibility of the distal tip 346 can be achieved by acombination of flexible lubricious materials and tapered shapes. Forexample, the length of the tip 346 can be kept shorter than 2 cm-3 cm,but maintain optimum deliverability due to a change in flexible materialfrom distal-most tip towards a more proximal region a distance away fromthe distal-most tip. In an implementation, the elongate body 360 isformed of PEBAX (polyether block amide) embedded silicone designed tomaintain the highest degree of flexibility. It should be appreciatedthat the wall thickness of the distal end of the luminal portion 222 canalso be made thin enough such that the lip formed by the distal end ofthe luminal portion 222 relative to the elongate body 360 is minimized.

As mentioned above, the elongate body 360 can be constructed to havevariable stiffness between the distal and proximal ends of the elongatebody 360. The flexibility of the elongate body 360 is highest at thedistal-most terminus of the distal tip 346 and can gradually transitionin flexibility to approach the flexibility of the distal end of theluminal portion 222, which is typically less flexible than thedistal-most terminus of the distal tip 346. Upon inserting the catheteradvancement element 300 through the catheter 200, the region of theelongate body 360 extending beyond the distal end of the luminal portion222 can be the most flexible and the region of the elongate body 360configured to be aligned with the distal end of the luminal portion 222during advancement in the vessel can have a substantially identicalflexibility as the distal end of the luminal portion 222 itself. Assuch, the flexibility of the distal end of the luminal portion 222 andthe flexibility of the body 360 just proximal to the extended portion(whether tapered or having no taper) can be substantially the same. Thisprovides a smooth transition in material properties to improve trackingof the catheter system through tortuous anatomy. Further, the moreproximal sections of the elongate body 360 can be even less flexible andincreasingly stiffer. It should be appreciated that the change inflexibility of the elongate body 360 can be a function of a materialdifference, a dimensional change such as through tapering, or acombination of the two. The elongate body 360 has a benefit over amicrocatheter in that it can have a relatively large outer diameter thatis just 0.003″-0.010″ smaller than the inner diameter of the distalluminal portion 222 of the catheter 200 and still maintain a high degreeof flexibility for navigating tortuous anatomy. When the gap between thetwo components is too tight (e.g. less than about 0.003″), the forceneeded to slide the catheter advancement element 300 relative to thecatheter 200 can result in damage to one or both of the components andincreases risk to the patient during the procedure. The gap results intoo tight of a fit to provide optimum relative sliding. When the gapbetween the two components is too loose (e.g. greater than about0.010″), the distal end of the catheter 200 forms a lip that is prone tocatch on branching vessels during advancement through tortuousneurovasculature, such as around the carotid siphon where the ophthalmicartery branches off.

The gap in ID/OD between the elongate body 360 and the distal luminalportion 222 can be in this size range (e.g. 0.003″-0.010″) along amajority of their lengths. For example, the elongate body 360 can have arelatively uniform outer diameter that is between about 0.048″ to about0.080″ from a proximal end region to a distal end region up to a pointwhere the taper of the distal tip 346 begins. Similarly, the distalluminal portion 222 of the catheter 200 can have a relatively uniforminner diameter that is between about 0.054″ to about 0.088″ from aproximal end region to a distal end region. As such, the differencebetween their respective inner and outer diameters along a majority oftheir lengths can be within this gap size range of 0.003″ to 0.010″. Itshould be appreciated, however, that the distal tip 346 of the elongatebody 360 that is tapered will have a larger gap size relative to theinner diameter of the distal luminal portion 222. During use, however,this tapered distal tip 346 is configured to extend distal to the distalend of the catheter 200 such that the region of the elongate body 360having an outer diameter sized to match the inner diameter of the distalluminal portion 222 is positioned within the lumen of the catheter 200such that it can minimize the lip at the distal end of the catheter 200.

The elongate body 360 can be formed of various materials that provide asuitable flexibility and lubricity. Example materials include highdensity polyethylene, 72 D PEBAX, 90 D PEBAX, or equivalent stiffnessand lubricity material. At least a portion of the elongate body 360 canbe reinforced to improve navigation and torqueing (e.g. braidedreinforcement layer). The flexibility of the elongate body 360 canincrease towards the distal tip 346 such that the distal region of theelongate body 360 is softer, more flexible, and articulates and bendsmore easily than a more proximal region. For example, a more proximalregion of the elongate body can have a bending stiffness that isflexible enough to navigate tortuous anatomy such as the carotid siphonwithout kinking. If the elongate body 360 has a braid reinforcementlayer along at least a portion of its length, the braid reinforcementlayer can terminate a distance proximal to the distal tip 346. Forexample, the distance from the end of the braid to the distal tip can beabout 10 cm to about 15 cm or from about 4 cm to about 10 cm or fromabout 4 cm up to about 15 cm.

In some implementations, the elongate body 360 can be generally tubularalong at least a portion of its length such that it has a single lumen368 extending parallel to a longitudinal axis of the catheteradvancement element 300 (see FIG. 7A-7C and also FIG. 10A-10C). In animplementation, the single lumen 368 of the elongate body 360 is sizedto accommodate a guidewire, however it should be appreciated that use ofthe catheter advancement element 300 generally eliminates the need for aguidewire lead. The guidewire can extend through the single lumen 368generally concentrically from a proximal opening to a distal openingthrough which the guidewire can extend. In some implementations, theproximal opening is at the proximal end of the catheter advancementelement 300 such that the catheter advancement element 300 is configuredfor over-the-wire (OTW) methodologies. In other implementations, theproximal opening is a rapid exchange opening 362 through a wall of thecatheter advancement element 300 such that the catheter advancementelement 300 is configured for rapid exchange rather than or in additionto OTW. In this implementation, the proximal opening 362 extends throughthe sidewall of the elongate body and is located a distance away from aproximal tab 364 and distal to the proximal portion 366 (see FIGS. 7A-7Band 7D). The proximal opening 362 can be located a distance of about 10cm from the distal tip 346 up to about 20 cm from the distal tip 346. Insome implementations, the proximal opening 362 can be located near aregion where the elongate body 360 is joined to the proximal portion366, for example, just distal to an end of the hypotube (see FIG. 7B).In other implementations, the proximal opening 362 is located moredistally such as about 10 cm to about 18 cm from the distal-most end ofthe elongate body 360 (see FIG. 7D). A proximal opening 362 that islocated closer to the distal tip 346 allows for easier removal of thecatheter advancement element 300 from the catheter 200 leaving theguidewire in place for a “rapid exchange” type of procedure. Rapidexchanges can rely on only a single person to perform the exchange. Thecatheter advancement element 300 can be readily substituted for anotherdevice using the same guidewire that remains in position. The singlelumen 368 of the elongate body 360 can be configured to receive aguidewire in the range of 0.014″ and 0.018″ diameter, or in the range ofbetween 0.014″ and 0.022″. In this implementation, the inner luminaldiameter of the elongate body 360 can be between 0.020″ and 0.024″. Theguidewire, the catheter advancement element 300, and the catheter 200can all be assembled co-axially for insertion through the working lumenof the guide sheath 400. The inner diameter of the lumen 368 of theelongate body 360 can be 0.019″ to about 0.021″.

FIG. 7D shows another implementation of the catheter advancement element300 configured for rapid exchange. Rapid exchange configurations candramatically shorten device length, decreases staffing requirements, andreduces fluoroscopy. As with other implementations described herein, thecatheter advancement element 300 can include a non-expandable, flexibleelongate body 360 coupled to a proximal portion 366 coupled to aproximal tab 364 or hub 375. As described elsewhere herein, the regionnear the distal tip 346 can be tapered such that the outer diametertapers over a length of about 1 cm to about 3 cm. In someimplementations, the distal taper length is 2.5 cm. In someimplementations, the distal tip 346 tapers from about 0.080″ to about0.031″. Also as described elsewhere herein, the distal tip 346 can beformed of a material having a hardness (e.g. 62 A and 35 D) thattransitions proximally towards increasingly harder materials having(e.g. 55 D and 72 D) up to the proximal portion 366. For example, FIG.7D illustrates segment 371 of the elongate body 360 including the distaltip 346 can have a hardness of 35 D and a length of about 10 cm to about12.5 cm. Segment 371 of the elongate body 360 including the distal tip346 can have a hardness of 62 A and a length of about 10 cm to about12.5 cm. Segment 372 of the elongate body 360 can have a hardness of 55D and have a length of about 5 cm to about 8 cm. Segment 373 of theelongate body 360 can have a hardness of 72 D can be about 25 cm toabout 35 cm in length. The three segments 371, 372, 373 combined canform an insert length of the elongate body 360 from where the proximalportion 366 couples to the elongate body 360 to the terminus of thedistal tip 346 that can be about 49 cm in length.

FIGS. 10A-10C illustrate an implementation of a catheter advancementelement 300 incorporating a reinforcement layer 380. As mentioned above,the reinforcement layer 380 can be a braid or other type ofreinforcement to improve the torqueability of the catheter advancementelement 300 and help to bridge the components of the catheteradvancement element 300 having such differences in flexibility. Thereinforcement layer 380 can bridge the transition from the rigid,proximal portion 366 to the flexible elongate body 360. In someimplementations, the reinforcement layer 380 can be a braid positionedbetween inner and outer layers of Pebax 382, 384 (see FIG. 10C). Thereinforcement layer 380 can terminate a distance proximal to the distaltip region 346. For example, FIG. 10A illustrates the elongate body 360having segment 371 and segment 373 located proximal to segment 371.Segment 371 can include the distal tip 346 having a hardness of at mostabout 35 D. Segment 371 is unreinforced polymer having a length of about4 cm up to about 12.5 cm. Segment 373 of the elongate body 360 locatedproximal to segment 371 can include the reinforcement layer 380 and canextend a total of about 37 cm up to the unreinforced distal segment 371.A proximal end region of the reinforcement layer 380 can overlap with adistal end region of the proximal portion 366 such that a small overlapof hypotube and reinforcement exists near the transition between theproximal portion 366 and the elongate body 360.

Again with respect to FIG. 7D, an entry port 362 for a proceduralguidewire 805 can be positioned a distance away from the distal-most endof the elongate body 360. In some implementations, the entry/exit port362 can be about 18 cm from the distal-most end creating a rapidexchange wire entry/exit segment 370. The outer diameter of the elongatebody 360 within segment 370 (segments 371 and 372) can be about0.080″-0.082″ whereas segment 373 proximal to this rapid exchange wireentry/exit segment 370 can have a step-down in outer diameter such asabout 0.062″-0.064″.

In other implementations, the entire catheter advancement element 300can be a tubular element configured to receive a guidewire through boththe proximal portion 366 as well as the elongate body 360. For example,the proximal portion 366 can be a hypotube or tubular element having alumen that communicates with the lumen 368 extending through theelongate body 360 (shown in FIG. 3). In some implementations, theproximal portion 366 can be a skived hypotube of stainless steel coatedwith PTFE having an outer diameter of 0.026″. In other implementations,the outer diameter can be between 0.024″ and 0.030″. In someimplementations, such as an over-the-wire version, the proximal portion366 can be a skived hypotube coupled to a proximal hub 375. The proximalportion 366 can extend eccentric or concentric to the distal luminalportion 222. As best shown in FIG. 7E, the proximal portion 366 can be astainless steel hypotube as described elsewhere herein. The proximalportion 366 can be a solid metal wire that is round or ovalcross-sectional shape. The proximal portion 366 can be a flattenedribbon of wire having a rectangular cross-sectional shape as describedelsewhere herein. The ribbon of wire can be curved into a circular,oval, c-shape, or quarter circle, or other cross-sectional shape alongan arc. The proximal portion 366 can have any of variety ofcross-sectional shapes whether or not a lumen extends therethrough,including a circular, oval, C-shaped, D-shape, or other shape. In someimplementations, the proximal portion 366 is a hypotube having a D-shapesuch that an inner-facing side is flat and an outer-facing side isrounded. The rounded side of the proximal portion 366 can be shaped toengage with a correspondingly rounded inner surface of the sheath 400.The hypotube can have a lubricious coating such as PTFE. The hypotubecan have an inner diameter of about 0.021″, an outer diameter of about0.0275″, and an overall length of about 94 cm providing a working lengthfor the catheter advancement element 300 that is about 143 cm. Includingthe proximal hub 375, the catheter advancement element 300 can have anoverall length of about 149 cm. In some implementations, the hypotubecan be a tapered part with a length of about 100 mm, starting proximalwith a thickness of 0.3 mm and ending with a thickness of 0.10 mm to0.15 mm. In still further implementations, the elongate body 360 can bea solid element coupled to the proximal portion 366 having no guidewirelumen.

As best shown in FIGS. 7F-7J, the proximal end of the hypotube can becoupled to a proximal hub 375. The proximal hub 375 can be anover-molded component having a luer thread 377 and a luer taper 378formed on an inside of the proximal hub 375. The proximal hub 375 canincorporate a tab 364 providing for easier gripping by a user. Theproximal hub 375 prevents advancement of the catheter advancementelement 300 and the catheter 200 beyond the distal tip of the basesheath 400 or guide catheter by limiting insertion into the proximal RHV434 providing critical functional and safety features for properoperation of the system 10.

At least a portion of the solid elongate body 360, such as the elongatedistal tip 346, can be formed of or embedded with or attached to amalleable material that skives down to a smaller dimension at a distalend. The distal tip 346 can be shaped to a desired angle or shapesimilar to how a guidewire may be used. The malleable length of theelongate body 360 can be at least about 1 cm, 3 cm, 5 cm, and up toabout 10 cm, 15 cm, or longer. In some implementations, the malleablelength can be about 1%, 2%, 5%, 10%, 20%, 25%, 50% or more of the totallength of the elongate body 360. In some implementations, the catheteradvancement element 300 can have a working length of about 140 cm toabout 143 cm and the elongate body 360 can have an insert length ofabout 49 cm. The insert length can be the PEBAX portion of the elongatebody 360 that is about 49.5 cm. As such, the malleable length of theelongate body 360 can be between about 0.5 cm to about 25 cm or more.The shape change can be a function of a user manually shaping themalleable length prior to insertion or the tip can be pre-shaped at thetime of manufacturing into a particular angle or curve. Alternatively,the shape change can be a reversible and actuatable shape change suchthat the tip forms the shape upon activation by a user such that the tipcan be used in a straight format until a shape change is desired by theuser. The catheter advancement element 300 can also include a formingmandrel extending through the lumen of the elongate body 360 such that aphysician at the time of use can mold the distal tip 346 into a desiredshape. As such, the moldable distal tip 346 can be incorporated onto anelongate body 360 that has a guidewire lumen.

It should be appreciated that the elongate body 360 can extend along theentire length of the catheter 200, including the distal luminal portion222 and the proximal extension 230 or the elongate body 360 canincorporate the proximal portion 366 that aligns generally side-by-sidewith the proximal extension 230 of the catheter 200, as described above.The proximal portion 366 of the elongate body 360 can be positionedco-axial with or eccentric to the elongate body 360. The proximalportion 366 of the elongate body 360 can have a lumen extending throughit. Alternatively, the portion 366 can be a solid rod or ribbon havingno lumen.

Again with respect to FIGS. 7A-7D, like the distal luminal portion 222of the catheter 200, the elongate body 360 can have one or moreradiopaque markers 344 along its length. The one or more markers 344 canvary in size, shape, and location. One or more markers 344 can beincorporated along one or more parts of the catheter advancement element300, such as a tip-to-tip marker, a tip-to-taper marker, an RHVproximity marker, a Fluoro-saver marker, or other markers providingvarious information regarding the relative position of the catheteradvancement element 300 and its components. In some implementations andas best shown in FIG. 7C, a distal end region can have a firstradiopaque marker 344 a and a second radiopaque marker 344 b can belocated to indicate the border between the tapering of the distal tip346 and the more proximal region of the elongate body 360 having auniform or maximum outer diameter. This provides a user with informationregarding an optimal extension of the distal tip 346 relative to thedistal end of the luminal portion 222 to minimize the lip at this distalend of the luminal portion 222 for advancement through tortuous anatomy.In other implementations, for example where the distal tip 346 is notnecessarily tapered, but instead has a change in overall flexibilityalong its length, the second radiopaque marker 344 b can be located toindicate the region where the relative flexibilities of the elongatebody 360 (or the distal tip 346 of the elongate body 360) and the distalend of the luminal portion 222 are substantially the same. The markermaterial may be a platinum/iridium band, a tungsten, platinum, ortantalum-impregnated polymer, or other radiopaque marker that does notimpact the flexibility of the distal tip 346 and elongate body 360. Insome implementations, the radiopaque markers are extruded PEBAX loadedwith tungsten for radiopacity. In some implementations, the proximalmarker band can be about 2.0 mm wide and the distal marker band can beabout 2.5 mm wide to provide discernable information about the distaltip 346.

As mentioned above, the proximal extension 230 of the catheter 200 caninclude a proximal tab 234 on the proximal end of the proximal extension230. Similarly, the proximal portion 366 coupled to the elongate body360 can include a tab 364. The tabs 234, 364 can be configured toremovably and adjustable connect to one another and/or connect to theircorresponding proximal portions. The coupling allows the catheteradvancement element 300 to reversibly couple with the catheter 200 tolock (and unlock) the relative extension of the distal luminal portion222 and the elongate body 360. This allows the catheter 200 and thecatheter advancement element 300 to be advanced as a single unit. In thelocked configuration, the tab 364 or proximal portion 366 can be engagedwith the catheter tab 234. In the unlocked configuration, the tab 364may be disengaged from the catheter tab 234. The tab 364 or proximalportion 366 may attach, e.g., click or lock into, the catheter tab 234in a fashion as to maintain the relationships of corresponding sectionof the elongate body 360 and the catheter 200 in the lockedconfiguration. It should be appreciated that the tab 364 can be afeature on the proximal hub 375 such as the hub 375 shown in FIGS.7F-7J.

Such locking may be achieved by, e.g., using a detent on the tab 364that snaps into place within a recess formed in the catheter tab 234, orvice versa. For example, the tab 234 of the catheter 200 can form a ringhaving a central opening extending therethrough. The tab 364 of the body360 can have an annular detent with a central post sized to insertthrough the central opening of the tab 234 such that such that the ringof the tab 234 is received within the annular detent of tab 364 forminga singular grasping element for a user to advance and/or withdraw thecatheter system through the access sheath. The tabs 234, 364 may beaffixed or may be slideable to accommodate different relative positionsbetween the elongate body 360 and the luminal portion 222 of thecatheter 200. In some implementations, a proximal end of the proximalextension 230 of the catheter 200 can include a coupling feature 334,such as clip, clamp, c-shaped element or other connector configured toreceive the proximal portion 366 of the catheter advancement element 300(see FIG. 2A). The coupling feature 334 can be configured to snaptogether with the proximal portion 366 through an interference fit suchthat a first level of force is needed in order to insert the proximalportion 366 into the clip of the tab 234 and a second, greater level offorce is needed to remove the proximal portion 366 from the clip of thetab 234. However, upon inserting the proximal portion 366 into thecoupling feature 334 the catheter advancement element 300 and thecatheter 200 can still be slideably adjusted relative to one anotheralong a longitudinal axis of the system. The amount of force needed toslideably adjust the relative position of the two components can be suchthat inadvertent adjustment is avoided and the relative position can bemaintained during use, but can be adjusted upon conscious modification.It should be appreciated that the configuration of the coupling betweenthe proximal portion 366 of the catheter advancement element 300 and theproximal extension 360 of the catheter 200 can vary. Generally, however,the coupling is configured to be reversible and adjustable while stillproviding adequate holding power between the two elements in a mannerthat is relatively user-friendly (e.g. allows for one-handed use) andorganizes the proximal ends of the components (e.g. prevents theproximal extension 360 and proximal portion 366 from becoming twistedand entangled with one another). It should also be appreciated that thecoupling feature 334 configured to prevent entanglement and aid in theorganization of the proximal portions can be integrated with the tabs orcan be a separate feature located along their proximal end region.

The catheter advancement element 300 can be placed in a lockedconfiguration with the catheter 200 configured for improved trackingthrough a tortuous and often diseased vasculature in acute ischemicstroke. Other configurations are considered herein. For example, theelongate body 360 can include one or more detents on an outer surface.The detents can be located near a proximal end region and/or a distalend region of the elongate body 360. The detents are configured to lockwith correspondingly-shaped surface features on the inner surface of theluminal portion 222 through which the elongate body 360 extends. Thecatheter advancement element 300 and the catheter 200 can haveincorporate more than a single point of locking connection between them.For example, a coupling feature 334, such as clip, clamp, c-shapedelement or other connector configured to hold together the catheteradvancement element 300 and proximal extension 230 or tab 234 of thecatheter 200 as described elsewhere herein.

In some implementations, the proximal extension 230 of the catheter 200can run alongside or within a specialized channel of the proximalportion 366. The channel can be located along a length of the proximalportion 366 and have a cross-sectional shape that matches across-sectional shape of the catheter proximal extension 230 such thatthe proximal extension 230 of the catheter 200 can be received withinthe channel and slide smoothly along the channel bi-directionally. Oncethe catheter 200 and elongate body 360 are fixed, the combined system,i.e., the catheter 200-catheter advancement element 300 may be deliveredto a target site, for example through the working lumen of the guidesheath 400 described elsewhere herein.

The catheter advancement element 300 (whether incorporating thereinforcement layer or not) loaded within the lumen of the catheter 200may be used to advance a catheter 200 to distal regions of the brain(e.g. level of the MCA). The traditional approach to the Circle ofWillis is to use a triaxial system including a guidewire placed within aconventional microcatheter placed within an intermediate catheter. Theentire coaxial system can extend through a base catheter or sheath. Thesheath is typically positioned such that the distal tip of the sheath isplaced in a high cervical carotid artery. The coaxial systems are oftenadvanced in unison up to about the terminal carotid artery where theconventional coaxial systems must then be advanced in a step-wisefashion in separate throws. This is due to the two sequential 180 degreeor greater turns (see FIGS. 1A-1C). The first turn is at the level ofthe petrous to the cavernous internal carotid artery. The second turn isat the terminal cavernous carotid artery as it passes through the bonyelements and reaches the bifurcation into the anterior cerebral arteryACA and middle cerebral artery MCA. This S-shape region is referred toherein as the “siphon” or “carotid siphon”. The ophthalmic artery arisesfrom the cerebral ICA, which represents a common point of catheter hangup in accessing the anterior circulation.

Conventional microcatheter systems can be advanced through to theanterior circulation over a guidewire. Because the inner diameter of theconventional microcatheter is significantly larger than the outerdiameter of the guidewire over which it is advanced, a lip can be formedon a distal end region of the system that can catch on these sidebranches during passage through the siphon. Thus, conventionalmicrocatheter systems (i.e. guidewire, microcatheter, and intermediatecatheter) are never advanced through both bends of the carotid siphonsimultaneously in a single smooth pass to distal target sites. Rather,the bends of the carotid siphon are taken one at a time in a step-wiseadvancement technique. For example, to pass through the carotid siphon,the conventional microcatheter is held fixed while the guidewire isadvanced alone a first distance (i.e. through the first turn of thesiphon). Then, the guidewire is held fixed while the conventionalmicrocatheter is advanced alone through the first turn over theguidewire. Then, the conventional microcatheter and guidewire are heldfixed while the intermediate catheter is advanced alone through thefirst turn over the microcatheter and guidewire. The process repeats inorder to pass through the second turn of the siphon, which generally isconsidered the more challenging turn into the cerebral vessel. Themicrocatheter and intermediate catheter are held fixed while theguidewire is advanced alone a second distance (i.e. through the secondturn of the siphon). Then, the guidewire and interventional catheter areheld fixed while the microcatheter is advanced alone through that secondturn over the guidewire. Then, the guidewire and the microcatheter areheld fixed while the interventional catheter is advanced alone throughthe second turn. This multi-stage, step-wise procedure is atime-consuming process that requires multiple people performing multiplehand changes on the components. For example, two hands to fix and pushthe components over each other forcing the user to stage the steps asdescribed above. The step-wise procedure is required because the steppedtransitions between these components (e.g. the guidewire, microcatheter,and intermediate catheter) makes advancement too challenging.

In contrast, the catheter 200 and catheter advancement element 300eliminate this multi-stage, step-wise component advancement procedure toaccess distal sites across the siphon. The catheter 200 and catheteradvancement element 300 can be advanced as a single unit through theboth turns of the carotid siphon CS. Both turns can be traversed in asingle smooth pass or throw to a target in a cerebral vessel without thestep-wise adjustment of their relative extensions and without relying onthe conventional step-wise advancement technique, as described abovewith conventional microcatheters. The catheter 200 having the catheteradvancement element 300 extending through it allows a user to advancethem in unison in the same relative position from the first bend of thesiphon through the second bend beyond the terminal cavernous carotidartery into the ACA and MCA. Importantly, the advancement of the twocomponents can be performed in a single smooth movement through bothbends without any change of hand position.

The catheter advancement element 300 can be in a juxtapositionedrelative to the catheter 200 that provides an optimum relative extensionbetween the two components for single smooth advancement. The catheteradvancement element 300 can be positioned through the lumen of thecatheter 200 such that its distal tip 346 extends beyond a distal end ofthe catheter 200. The distal tip 346 of the catheter advancement element300 eliminates the stepped transition between the inner member and theouter catheter 200 thereby avoiding issues with catching on branchingvessels within the region of the vasculature such that the catheter 200may easily traverse the multiple angulated turns of the carotid siphonCS. The optimum relative extension, for example, can be the distal tip346 of the elongate body 360 extending distal to a distal end of thecatheter 200 as described elsewhere herein. A length of the distal tip346 extending distal to the distal end can be between 0.5 cm and about 3cm. This juxtaposition can be a locked engagement with a mechanicalelement or simply by a user holding the two components together.

The components can be advanced together with a guidewire, over aguidewire pre-positioned, or without any guidewire at all. In someimplementations, the guidewire can be pre-assembled with the catheteradvancement element 300 and catheter 200 such that the guidewire extendsthrough a lumen of the catheter advancement element 300, which is loadedthrough a lumen of the catheter 200, all prior to insertion into thepatient. The pre-assembled components can be simultaneously insertedinto the sheath 400 and advanced together up through and past the turnsof the carotid siphon.

The optimum relative extension of the catheter 200 and catheteradvancement element 300 can be based additionally on the staggering ofmaterial transitions. FIG. 11 is a schematic illustrating approximatelocations of the material transitions in the catheter advancementelement 300 and the approximate locations of the material transitions inthe catheter 200. For example, the catheter advancement element 300 caninclude a proximal portion 366, which can be a hypotube, having ahardness of approximately 72 D. The proximal portion 366 transitions ata location 1101 a to a region having a material hardness of about 55 Dthat transitions at a location 1101 b to a region having a materialhardness of about 35 D that transitions at a location 1101 c to a regionhave a material hardness of 35 D. Similarly, the catheter 200 caninclude a proximal extension 230 that is a stainless steel ribbon. Theproximal extension 230 transitions at a location 1103 a to a regionhaving a hardness of 72 D that transitions at a location 1103 b to aregion having a hardness of 55 D that transitions at a location 1103 cto a region having a material hardness of about 40 D that transitions ata location 1103 d to a region having a material hardness of about 35 Dthat transitions at a location 1103 e to a region have a materialhardness of 25 D that transitions at a location 1103 f to a regionhaving a material hardness of about 85 A that transitions at a location1103 g to a region having a material hardness of about 80 A. Adistal-most region of the catheter advancement element 300 can be formedof Tecothane having a material hardness of about 62 A. The locations1101 of the catheter advancement element 300 and the locations 1103 ofthe catheter 200 can be staggered such that the locations are off-setfrom one another. It should be appreciated that more or fewer materialtransitions may exist within the catheter advancement element andcatheter.

The catheter 200 and catheter advancement element 300 can bepre-assembled at the time of manufacturing such that an optimum lengthof the catheter advancement element 300 extends distal to the distal endof catheter 200 and/or the material transitions are staggered. Anoptimum length of extension can be such that the entire length of thetapered distal tip of the catheter advancement element 300 extendsoutside the distal end of the catheter 200 such that the uniform outerdiameter of the catheter advancement element 300 aligns substantiallywith the distal end of the catheter 200. This can result in the greatestouter diameter of the elongate body 360 aligned substantially with thedistal end of the catheter 200 such that it remains inside the lumen ofthe catheter 200 and only the tapered region of the distal tip 346extends distal to the lumen of the catheter 200. This relativearrangement provide the best arrangement for advancement throughtortuous vessels where a lip at the distal end of the system would posethe greatest difficulty. This optimal pre-assembled arrangement can bemaintained by a coupler configured to engage with both the proximalextension 230 of the catheter 200 and the proximal portion 366 of thecatheter advancement element 300. The coupler can be used during aprocedure as described elsewhere herein. Alternatively, the coupler canbe removed prior to a procedure.

FIG. 12 illustrates an implementation of a coupler 1201 configured to beremoved prior to a procedure. The coupler 1201 can be a temporarycoupler configured to engage the catheter 200 and catheter advancementelement 300 only at the time of manufacturing and/or during storage. Insome implementations, the coupler 1201 can be a disc having a layer ofadhesive material on one side. The coupler 1201 is configured to captureboth the proximal extension 230 of the catheter 200 and the proximalportion 366 of the catheter advancement element 300 and maintain theoptimal pre-assembled extension arrangement. The coupler 1201 can betorn away from the proximal extension 230 and the proximal portion 366with ease and without leaving any residue. The coupler 1201 can a discof plastic material, such as polyimide. The hemispheres of the disk aredesigned to fold over onto themselves until the adhesive side of eachhemisphere engages one another thereby trapping the hypotubes of theproximal extension 230 and proximal portion 366 of the catheter 200 andcatheter advancement element 300, respectively, therebetween along anequator of the disc. The disc can include a pair of notches 1203 nearthe equator such that the overall shape of the disc is bi-lobed. Thedisc can include a first rounded lobe 1202 a on one side of the pair ofnotches 1203 and a second rounded lobe 1202 b on the opposite side ofthe pair of notches 1203, each of the first and second lobe 1202 a, 1202b having matching shapes. The hypotubes can be captured along theequator of the disc between the first and second lobes 1202 a, 1202 bfolding over onto each other such that their adhesive sides can capturethe hypotubes. The apex of each notch 1203 aligns with the equator ofthe disc and each can include a cut or notch extension 1205 extendingtoward the center of the disc. The apex of each notch 1203 incoordination with the notch extensions 1205 aid in getting the tearstarted creating a stress concentration tear-away location when thecatheter system is ready to be used. The notch extensions 1205 help todirect the tear direction. The coupler 1201 is thereby engaged with boththe hypotube proximal extension 230 of the catheter 200 and the hypotubeproximal body 330 of the catheter advancement element 300, which isinserted through the lumen of the catheter 200. The coupled engagementallows the two components engaged with one another to be easily insertedinto the packaging hoop while maintaining the optimal relative extensionof the components. The coupler 1201 avoids catching on the packaginghoop due to the rounded, smooth surfaces and lack of edges to catch.Prior to use of the catheter system 100, a user can remove the catheter200/catheter advancement element 300 from the packaging hoop. Thecoupler 1201 can be torn away from the hypotubes by a user pulling onthe folded over lobes 1202 a, 1202 b adhered to one another. The entirecoupler 1201 is thereby removed from the hypotubes without leaving anyresidue on the hypotubes. The system is immediately ready for insertionat an optimal pre-assembled relative extension.

The dimensions of the coupler 1201 are such that they provide ampleengagement with the hypotubes thereby locking them together andmaintaining the relative extension yet not so large as to negativelyimpact storage within the packaging hoop. The disc of the coupler 1201can have a diameter that is about 0.75″ to about 1″. The disc can berelatively thin such as between about 0.0005″ to about 0.0015″ thickpolyimide. In some implementations, the polyimide disc is about 0.001″thick. One side of the discs can include a layer of adhesive, such assilicone adhesive. The adhesive can be about 0.0015″ thick. Each side ofthe notches 1203 can have a length l extending between the outerperimeter of the disc and the apex of the notch 1203. The length can beabout 0.200″ long. The sides can form an angle θ relative to one anotherthat is between about 50 and 70 degrees, preferably about 60 degrees.

It should be appreciated that the catheter and the catheter advancementelement may be releaseably, pre-packaged in a locked position accordingto any of a variety of methods (e.g. shrink-wrap, and other knownmethods).

Materials

One or more components of the catheters described herein may include orbe made from a variety of materials including one or more of a metal,metal alloy, polymer, a metal-polymer composite, ceramics, hydrophilicpolymers, polyacrylamide, polyethers, polyamides, polyethylenes,polyurethanes, copolymers thereof, polyvinyl chloride (PVC), PEO,PEO-impregnated polyurethanes such as Hydrothane, Tecophilicpolyurethane, Tecothane, PEO soft segmented polyurethane blended withTecoflex, thermoplastic starch, PVP, and combinations thereof, and thelike, or other suitable materials.

Some examples of suitable metals and metal alloys include stainlesssteel, such as 304V, 304L, and 316LV stainless steel; mild steel;nickel-titanium alloy such as linear-elastic and/or super-elasticnitinol; other nickel alloys such as nickel-chromium-molybdenum alloys(e.g., UNS: N06625 such as INCONEL® 625, UNS: N06022 such as HASTELLOY®C-22®, UNS: N10276 such as HASTELLOY® C276®, other HASTELLOY® alloys,and the like), nickel-copper alloys (e.g., UNS: N04400 such as MONEL®400, NICKELVAC® 400, NICORROS® 400, and the like),nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such asMP35-N® and the like), nickel-molybdenum alloys (e.g., UNS: N10665 suchas HASTELLOY® ALLOY B2®), other nickel-chromium alloys, othernickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-ironalloys, other nickel-copper alloys, other nickel-tungsten or tungstenalloys, and the like; cobalt-chromium alloys; cobalt-chromium-molybdenumalloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like);platinum enriched stainless steel; titanium; combinations thereof; andthe like; or any other suitable material and as described elsewhereherein.

Inner liner materials of the catheters described herein can include lowfriction polymers such as PTFE (polytetrafluoroethylene) or FEP(fluorinated ethylene propylene), PTFE with polyurethane layer(Tecoflex). Reinforcement layer materials of the catheters describedherein can be incorporated to provide mechanical integrity for applyingtorque and/or to prevent flattening or kinking such as metals includingstainless steel, Nitinol, Nitinol braid, helical ribbon, helical wire,cut stainless steel, or the like, or stiff polymers such as PEEK.Reinforcement fiber materials of the catheters described herein caninclude various high tenacity polymers like Kevlar, polyester,meta-para-aramide, PEEK, single fiber, multi-fiber bundles, high tensilestrength polymers, metals, or alloys, and the like. Outer jacketmaterials of the catheters described herein can provide mechanicalintegrity and can be contracted of a variety of materials such aspolyethylene, polyurethane, PEBAX, nylon, Tecothane, and the like. Othercoating materials of the catheters described herein include paralene,Teflon, silicone, polyimide-polytetrafluoroetheylene, and the like.

Implementations describe catheters and delivery systems and methods todeliver catheters to target anatomies. However, while someimplementations are described with specific regard to deliveringcatheters to a target vessel of a neurovascular anatomy such as acerebral vessel, the implementations are not so limited and certainimplementations may also be applicable to other uses. For example, thecatheters can be adapted for delivery to different neuroanatomies, suchas subclavian, vertebral, carotid vessels as well as to the coronaryanatomy or peripheral vascular anatomy, to name only a few possibleapplications. It should also be appreciated that although the systemsdescribed herein are described as being useful for treating a particularcondition or pathology, that the condition or pathology being treatedmay vary and are not intended to be limiting. Use of the terms“embolus,” “embolic,” “emboli,” “thrombus,” “occlusion,” etc. thatrelate to a target for treatment using the devices described herein arenot intended to be limiting. The terms may be used interchangeably andcan include, but are not limited to a blood clot, air bubble, smallfatty deposit, or other object carried within the bloodstream to adistant site or formed at a location in a vessel. The terms may be usedinterchangeably herein to refer to something that can cause a partial orfull occlusion of blood flow through or within the vessel.

In various implementations, description is made with reference to thefigures. However, certain implementations may be practiced without oneor more of these specific details, or in combination with other knownmethods and configurations. In the description, numerous specificdetails are set forth, such as specific configurations, dimensions, andprocesses, in order to provide a thorough understanding of theimplementations. In other instances, well-known processes andmanufacturing techniques have not been described in particular detail inorder to not unnecessarily obscure the description. Reference throughoutthis specification to “one embodiment,” “an embodiment,” “oneimplementation, “an implementation,” or the like, means that aparticular feature, structure, configuration, or characteristicdescribed is included in at least one embodiment or implementation.Thus, the appearance of the phrase “one embodiment,” “an embodiment,”“one implementation, “an implementation,” or the like, in various placesthroughout this specification are not necessarily referring to the sameembodiment or implementation. Furthermore, the particular features,structures, configurations, or characteristics may be combined in anysuitable manner in one or more implementations.

The use of relative terms throughout the description may denote arelative position or direction. For example, “distal” may indicate afirst direction away from a reference point. Similarly, “proximal” mayindicate a location in a second direction opposite to the firstdirection. However, such terms are provided to establish relative framesof reference, and are not intended to limit the use or orientation ofthe catheters and/or delivery systems to a specific configurationdescribed in the various implementations.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of what is claimed or of what maybe claimed, but rather as descriptions of features specific toparticular embodiments. Certain features that are described in thisspecification in the context of separate embodiments can also beimplemented in combination in a single embodiment. Conversely, variousfeatures that are described in the context of a single embodiment canalso be implemented in multiple embodiments separately or in anysuitable sub-combination. Moreover, although features may be describedabove as acting in certain combinations and even initially claimed assuch, one or more features from a claimed combination can in some casesbe excised from the combination, and the claimed combination may bedirected to a sub-combination or a variation of a sub-combination.Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Only a few examples and implementations are disclosed.Variations, modifications and enhancements to the described examples andimplementations and other implementations may be made based on what isdisclosed.

In the descriptions above and in the claims, phrases such as “at leastone of” or “one or more of” may occur followed by a conjunctive list ofelements or features. The term “and/or” may also occur in a list of twoor more elements or features. Unless otherwise implicitly or explicitlycontradicted by the context in which it is used, such a phrase isintended to mean any of the listed elements or features individually orany of the recited elements or features in combination with any of theother recited elements or features. For example, the phrases “at leastone of A and B;” “one or more of A and B;” and “A and/or B” are eachintended to mean “A alone, B alone, or A and B together.” A similarinterpretation is also intended for lists including three or more items.For example, the phrases “at least one of A, B, and C;” “one or more ofA, B, and C;” and “A, B, and/or C” are each intended to mean “A alone, Balone, C alone, A and B together, A and C together, B and C together, orA and B and C together.”

Use of the term “based on,” above and in the claims is intended to mean,“based at least in part on,” such that an unrecited feature or elementis also permissible.

What is claimed is:
 1. A catheter system for performing a medicalprocedure in an intracranial vessel of a patient, the system comprising:a catheter comprising: a flexible distal luminal portion having aproximal end, a proximal end region, a proximal opening, a distal end,and a lumen extending between the proximal end and the distal end; and aproximal extension extending proximally from a point of attachmentadjacent the proximal opening, wherein the proximal extension is lessflexible than the flexible distal luminal portion and is configured tocontrol movement of the catheter, wherein the proximal extension has anouter diameter at the point of attachment that is smaller than an outerdiameter of the distal luminal portion at the point of attachment; and acatheter advancement element comprising: a flexible elongate body havinga proximal end region, an outer diameter, a tapered distal tip portion,a distal opening, and a single lumen extending longitudinally throughthe flexible elongate body to the distal opening; and a proximal portionextending proximally from the proximal end region to a proximal-most endof the catheter advancement element, wherein the catheter advancementelement is sized to be positioned through the proximal opening of theflexible distal luminal portion into the catheter lumen such that thetapered distal tip portion extends distal to the distal end of thedistal luminal portion, and wherein the flexible distal luminal portionand the proximal extension are configured to pass through a guidesheath, and wherein the distal luminal portion of the catheter has alength that is greater than 40 cm up to less than a working length ofthe guide sheath through which the system is advanced, the lengthsufficient to allow the distal end of the distal luminal portion toreach a target site within the intracranial vessel and the point ofattachment between the distal luminal portion and the proximal extensionbe positioned within a vessel proximal to the brachiocephalic take-off.2. The system of claim 1, wherein the length of the distal luminalportion is sufficient to position the distal end of the distal luminalportion distal to the carotid siphon when the point of attachment ispositioned proximal to the brachiocephalic take-off.
 3. The system ofclaim 1, wherein the proximal portion of the catheter advancementelement is coupled to the proximal end region of the flexible elongatebody at a point of attachment, the proximal portion extending proximallyfrom the point of attachment to the proximal-most end of the catheteradvancement element.
 4. The system of claim 1, wherein the proximalportion of the catheter advancement element has a single lumen extendingthrough an entire length of the proximal portion that communicates withthe single lumen of the elongate body.
 5. The system of claim 3, whereinthe elongate body has a length sufficient to allow the point ofattachment between the elongate body and the proximal portion to remainwithin or proximal to the aortic arch when assembled with the catheter,the distal end of the catheter positioned near the target site withinthe intracranial vessel.
 6. The system of claim 5, wherein the proximalopening of the flexible elongate body is through a sidewall of theflexible elongate body and is located a distance distal to the proximalportion of the catheter advancement element coupled to the proximal endregion.
 7. The system of claim 6, wherein the distance is about 10 cmfrom the distal tip portion up to about 20 cm from the distal tipportion.
 8. The system of claim 1, wherein the assembled catheter systemis pre-packaged with the catheter advancement element positioned withinthe lumen of the distal luminal portion such that the proximal portionof the flexible elongate body is locked with the proximal extension ofthe catheter.
 9. The system of claim 1, wherein at least a portion ofthe proximal extension of the catheter is color-coded.
 10. The system ofclaim 1, wherein the single lumen of the flexible elongate body is sizedto accommodate a guidewire.
 11. The system of claim 10, wherein theflexible elongate body comprises a proximal opening sized to accommodatethe guidewire.
 12. The system of claim 11, wherein the proximal openingof the flexible elongate body is located within the proximal end regionof the flexible elongate body.
 13. The system of claim 1, wherein aflexibility of the flexible elongate body transitions to be lessflexible proximally towards the proximal portion forming a firstplurality of material transitions.
 14. The system of claim 1, whereinthe distal tip portion comprises a material having a material hardnessthat is no more than 35 D, and wherein the proximal end region of theelongate body comprises a material having a material hardness that isbetween 55 D to 72 D.
 15. The system of claim 1, wherein the elongatebody comprises a first segment including the distal tip portion having ahardness of no more than 35 D, wherein the elongate body comprises asecond segment located proximal to the first segment having a hardnessof no more than 55 D, and wherein the elongate body comprises a thirdsegment located proximal to the second segment having a hardness of nomore than 72 D.
 16. The system of claim 15, wherein the proximal portioncouples to the elongate body within the third segment.
 17. The system ofclaim 15, wherein the first segment is unreinforced and the thirdsegment is reinforced.
 18. The system of claim 17, wherein the secondsegment is at least partially reinforced.
 19. The system of claim 15,wherein the first, second, and third segments combine to form an insertlength of the elongate body.
 20. The system of claim 1, wherein aflexibility of the flexible distal luminal portion transitions to beless flexible proximally towards the proximal extension, wherein theflexible distal luminal portion comprises a second plurality of materialtransitions, wherein the flexible elongate body is positioned within thelumen of the catheter such that the distal tip portion of the flexibleelongate body extends distally beyond the distal end of the cathetersuch that the first plurality of material transitions of the flexibleelongate body are staggered relative to and do not overlap with thesecond plurality of material transitions of the flexible distal luminalportion.
 21. The system of claim 1, wherein the length of the distalluminal portion allows for the distal end of the distal luminal portionto extend distal to a carotid siphon into the cerebral portion of aninternal carotid artery while the proximal end of the distal luminalportion remains within the descending aorta.
 22. The system of claim 1,wherein the lumen of the distal luminal portion of the catheter isdefined by a wall and a distal end region of the proximal extension issandwiched within layers of the wall of the distal luminal portion. 23.The system of claim 1, wherein the flexible elongate body incorporates asegment located distal to the proximal end region and proximal to thetapered distal tip portion, wherein the outer diameter of the flexibleelongate body is within the segment, and wherein an outer diameter ofthe proximal end region is smaller than the outer diameter of theflexible elongate body within the segment.
 24. The system of claim 1,wherein the proximal portion of the catheter advancement element and theproximal extension of the catheter extend side-by-side when assembled asa system.
 25. The system of claim 1, wherein the proximal portion of thecatheter advancement element comprises a hypotube having a distal endcoupled to the flexible elongate body.
 26. The system of claim 1,wherein the proximal portion is a solid metal wire or ribbon.
 27. Thesystem of claim 1, further comprising a tab positioned on a proximal endof the proximal extension of the catheter, wherein the tab is positionedrelative to the proximal opening to prevent over-insertion of thecatheter relative to the guide sheath so as to maintain the proximalopening within the guide sheath.
 28. The system of claim 27, wherein thetab is sized to abut against a connector on the guide sheath preventingfurther advancement of the distal luminal portion of the catheterthrough the guide sheath.